StringUtils (Commons Lang 3.1 API)

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org.apache.commons.lang3
Class StringUtils

java.lang.Object
  org.apache.commons.lang3.StringUtils

public class StringUtils
extends Object
extends Object

Operations on String that are null safe.

IsEmpty/IsBlank - checks if a String contains text
Trim/Strip - removes leading and trailing whitespace
Equals - compares two strings null-safe
startsWith - check if a String starts with a prefix null-safe
endsWith - check if a String ends with a suffix null-safe
IndexOf/LastIndexOf/Contains - null-safe index-of checks
IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
Substring/Left/Right/Mid - null-safe substring extractions
SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
Split/Join - splits a String into an array of substrings and vice versa
Remove/Delete - removes part of a String
Replace/Overlay - Searches a String and replaces one String with another
Chomp/Chop - removes the last part of a String
LeftPad/RightPad/Center/Repeat - pads a String
UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
CountMatches - counts the number of occurrences of one String in another
IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
DefaultString - protects against a null input String
Reverse/ReverseDelimited - reverses a String
Abbreviate - abbreviates a string using ellipsis
Difference - compares Strings and reports on their differences
LevenshteinDistance - the number of changes needed to change one String into another

The StringUtils class defines certain words related to String handling.

null - null
empty - a zero-length string ("")
space - the space character (' ', char 32)
whitespace - the characters defined by Character.isWhitespace(char)
trim - the characters <= 32 as in String.trim()

StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils.

Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

#ThreadSafe#

Since:: 1.0
Version:: $Id: StringUtils.java 1199894 2011-11-09 17:53:59Z ggregory $
See Also:: String

Field Summary
`static String`	`EMPTY` The empty String `""`.
`static int`	`INDEX_NOT_FOUND` Represents a failed index search.

Constructor Summary
`StringUtils()` `StringUtils` instances should NOT be constructed in standard programming.

Method Summary

static String abbreviate(String str, int maxWidth)
Abbreviates a String using ellipses.

static String abbreviate(String str, int offset, int maxWidth)
Abbreviates a String using ellipses.

static String abbreviateMiddle(String str, String middle, int length)
Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.

static String capitalize(String str)
Capitalizes a String changing the first letter to title case as per Character.toTitleCase(char).

static String center(String str, int size)
Centers a String in a larger String of size size using the space character (' ').

static String center(String str, int size, char padChar)
Centers a String in a larger String of size size.

static String center(String str, int size, String padStr)
Centers a String in a larger String of size size.

static String chomp(String str)
Removes one newline from end of a String if it's there, otherwise leave it alone.

static String chomp(String str, String separator)
Deprecated. This feature will be removed in Lang 4.0, use removeEnd(String, String) instead

static String chop(String str)
Remove the last character from a String.

static boolean contains(CharSequence seq, CharSequence searchSeq)
Checks if CharSequence contains a search CharSequence, handling null.

static boolean contains(CharSequence seq, int searchChar)
Checks if CharSequence contains a search character, handling null.

static boolean containsAny(CharSequence cs, char... searchChars)
Checks if the CharSequence contains any character in the given set of characters.

static boolean containsAny(CharSequence cs, CharSequence searchChars)
Checks if the CharSequence contains any character in the given set of characters.

static boolean containsIgnoreCase(CharSequence str, CharSequence searchStr)
Checks if CharSequence contains a search CharSequence irrespective of case, handling null.

static boolean containsNone(CharSequence cs, char... searchChars)
Checks that the CharSequence does not contain certain characters.

static boolean containsNone(CharSequence cs, String invalidChars)
Checks that the CharSequence does not contain certain characters.

static boolean containsOnly(CharSequence cs, char... valid)
Checks if the CharSequence contains only certain characters.

static boolean containsOnly(CharSequence cs, String validChars)
Checks if the CharSequence contains only certain characters.

static boolean containsWhitespace(CharSequence seq)
Check whether the given CharSequence contains any whitespace characters.

static int countMatches(CharSequence str, CharSequence sub)
Counts how many times the substring appears in the larger string.

static



<T extends CharSequence> 


T

defaultIfBlank(T str,
                             T defaultStr)

Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value of defaultStr.

static



<T extends CharSequence> 


T

defaultIfEmpty(T str,
                             T defaultStr)

Returns either the passed in CharSequence, or if the CharSequence is empty or null, the value of defaultStr.

static String defaultString(String str)
Returns either the passed in String, or if the String is null, an empty String ("").

static String defaultString(String str, String defaultStr)
Returns either the passed in String, or if the String is null, the value of defaultStr.

static String deleteWhitespace(String str)
Deletes all whitespaces from a String as defined by Character.isWhitespace(char).

static String difference(String str1, String str2)
Compares two Strings, and returns the portion where they differ.

static boolean endsWith(CharSequence str, CharSequence suffix)
Check if a CharSequence ends with a specified suffix.

static boolean endsWithAny(CharSequence string, CharSequence... searchStrings)
Check if a CharSequence ends with any of an array of specified strings.

static boolean endsWithIgnoreCase(CharSequence str, CharSequence suffix)
Case insensitive check if a CharSequence ends with a specified suffix.

static boolean equals(CharSequence cs1, CharSequence cs2)
Compares two CharSequences, returning true if they are equal.

static boolean equalsIgnoreCase(CharSequence str1, CharSequence str2)
Compares two CharSequences, returning true if they are equal ignoring the case.

static String getCommonPrefix(String... strs)
Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.

static int getLevenshteinDistance(CharSequence s, CharSequence t)
Find the Levenshtein distance between two Strings.

static int getLevenshteinDistance(CharSequence s, CharSequence t, int threshold)
Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.

static int indexOf(CharSequence seq, CharSequence searchSeq)
Finds the first index within a CharSequence, handling null.

static int indexOf(CharSequence seq, CharSequence searchSeq, int startPos)
Finds the first index within a CharSequence, handling null.

static int indexOf(CharSequence seq, int searchChar)
Finds the first index within a CharSequence, handling null.

static int indexOf(CharSequence seq, int searchChar, int startPos)
Finds the first index within a CharSequence from a start position, handling null.

static int indexOfAny(CharSequence cs, char... searchChars)
Search a CharSequence to find the first index of any character in the given set of characters.

static int indexOfAny(CharSequence str, CharSequence... searchStrs)
Find the first index of any of a set of potential substrings.

static int indexOfAny(CharSequence cs, String searchChars)
Search a CharSequence to find the first index of any character in the given set of characters.

static int indexOfAnyBut(CharSequence cs, char... searchChars)
Searches a CharSequence to find the first index of any character not in the given set of characters.

static int indexOfAnyBut(CharSequence seq, CharSequence searchChars)
Search a CharSequence to find the first index of any character not in the given set of characters.

static int indexOfDifference(CharSequence... css)
Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.

static int indexOfDifference(CharSequence cs1, CharSequence cs2)
Compares two CharSequences, and returns the index at which the CharSequences begin to differ.

static int indexOfIgnoreCase(CharSequence str, CharSequence searchStr)
Case in-sensitive find of the first index within a CharSequence.

static int indexOfIgnoreCase(CharSequence str, CharSequence searchStr, int startPos)
Case in-sensitive find of the first index within a CharSequence from the specified position.

static boolean isAllLowerCase(CharSequence cs)
Checks if the CharSequence contains only lowercase characters.

static boolean isAllUpperCase(CharSequence cs)
Checks if the CharSequence contains only uppercase characters.

static boolean isAlpha(CharSequence cs)
Checks if the CharSequence contains only Unicode letters.

static boolean isAlphanumeric(CharSequence cs)
Checks if the CharSequence contains only Unicode letters or digits.

static boolean isAlphanumericSpace(CharSequence cs)
Checks if the CharSequence contains only Unicode letters, digits or space (' ').

static boolean isAlphaSpace(CharSequence cs)
Checks if the CharSequence contains only Unicode letters and space (' ').

static boolean isAsciiPrintable(CharSequence cs)
Checks if the CharSequence contains only ASCII printable characters.

static boolean isBlank(CharSequence cs)
Checks if a CharSequence is whitespace, empty ("") or null.

static boolean isEmpty(CharSequence cs)
Checks if a CharSequence is empty ("") or null.

static boolean isNotBlank(CharSequence cs)
Checks if a CharSequence is not empty (""), not null and not whitespace only.

static boolean isNotEmpty(CharSequence cs)
Checks if a CharSequence is not empty ("") and not null.

static boolean isNumeric(CharSequence cs)
Checks if the CharSequence contains only Unicode digits.

static boolean isNumericSpace(CharSequence cs)
Checks if the CharSequence contains only Unicode digits or space (' ').

static boolean isWhitespace(CharSequence cs)
Checks if the CharSequence contains only whitespace.

static String join(Iterable<?> iterable, char separator)
Joins the elements of the provided Iterable into a single String containing the provided elements.

static String join(Iterable<?> iterable, String separator)
Joins the elements of the provided Iterable into a single String containing the provided elements.

static String join(Iterator<?> iterator, char separator)
Joins the elements of the provided Iterator into a single String containing the provided elements.

static String join(Iterator<?> iterator, String separator)
Joins the elements of the provided Iterator into a single String containing the provided elements.

static String join(Object[] array, char separator)
Joins the elements of the provided array into a single String containing the provided list of elements.

static String join(Object[] array, char separator, int startIndex, int endIndex)
Joins the elements of the provided array into a single String containing the provided list of elements.

static String join(Object[] array, String separator)
Joins the elements of the provided array into a single String containing the provided list of elements.

static String join(Object[] array, String separator, int startIndex, int endIndex)
Joins the elements of the provided array into a single String containing the provided list of elements.

static



<T> String

join(T... elements)
Joins the elements of the provided array into a single String containing the provided list of elements.

static int lastIndexOf(CharSequence seq, CharSequence searchSeq)
Finds the last index within a CharSequence, handling null.

static int lastIndexOf(CharSequence seq, CharSequence searchSeq, int startPos)
Finds the first index within a CharSequence, handling null.

static int lastIndexOf(CharSequence seq, int searchChar)
Finds the last index within a CharSequence, handling null.

static int lastIndexOf(CharSequence seq, int searchChar, int startPos)
Finds the last index within a CharSequence from a start position, handling null.

static int lastIndexOfAny(CharSequence str, CharSequence... searchStrs)
Find the latest index of any of a set of potential substrings.

static int lastIndexOfIgnoreCase(CharSequence str, CharSequence searchStr)
Case in-sensitive find of the last index within a CharSequence.

static int lastIndexOfIgnoreCase(CharSequence str, CharSequence searchStr, int startPos)
Case in-sensitive find of the last index within a CharSequence from the specified position.

static int lastOrdinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal)
Finds the n-th last index within a String, handling null.

static String left(String str, int len)
Gets the leftmost len characters of a String.

static String leftPad(String str, int size)
Left pad a String with spaces (' ').

static String leftPad(String str, int size, char padChar)
Left pad a String with a specified character.

static String leftPad(String str, int size, String padStr)
Left pad a String with a specified String.

static int length(CharSequence cs)
Gets a CharSequence length or 0 if the CharSequence is null.

static String lowerCase(String str)
Converts a String to lower case as per String.toLowerCase().

static String lowerCase(String str, Locale locale)
Converts a String to lower case as per String.toLowerCase(Locale).

static String mid(String str, int pos, int len)
Gets len characters from the middle of a String.

static String normalizeSpace(String str)
Similar to http://www.w3.org/TR/xpath/#function-normalize -space

static int ordinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal)
Finds the n-th index within a CharSequence, handling null.

static String overlay(String str, String overlay, int start, int end)
Overlays part of a String with another String.

static String remove(String str, char remove)
Removes all occurrences of a character from within the source string.

static String remove(String str, String remove)
Removes all occurrences of a substring from within the source string.

static String removeEnd(String str, String remove)
Removes a substring only if it is at the end of a source string, otherwise returns the source string.

static String removeEndIgnoreCase(String str, String remove)
Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.

static String removeStart(String str, String remove)
Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.

static String removeStartIgnoreCase(String str, String remove)
Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.

static String repeat(char ch, int repeat)
Returns padding using the specified delimiter repeated to a given length.

static String repeat(String str, int repeat)
Repeat a String repeat times to form a new String.

static String repeat(String str, String separator, int repeat)
Repeat a String repeat times to form a new String, with a String separator injected each time.

static String replace(String text, String searchString, String replacement)
Replaces all occurrences of a String within another String.

static String replace(String text, String searchString, String replacement, int max)
Replaces a String with another String inside a larger String, for the first max values of the search String.

static String replaceChars(String str, char searchChar, char replaceChar)
Replaces all occurrences of a character in a String with another.

static String replaceChars(String str, String searchChars, String replaceChars)
Replaces multiple characters in a String in one go.

static String replaceEach(String text, String[] searchList, String[] replacementList)
Replaces all occurrences of Strings within another String.

static String replaceEachRepeatedly(String text, String[] searchList, String[] replacementList)
Replaces all occurrences of Strings within another String.

static String replaceOnce(String text, String searchString, String replacement)
Replaces a String with another String inside a larger String, once.

static String reverse(String str)
Reverses a String as per StringBuilder.reverse().

static String reverseDelimited(String str, char separatorChar)
Reverses a String that is delimited by a specific character.

static String right(String str, int len)
Gets the rightmost len characters of a String.

static String rightPad(String str, int size)
Right pad a String with spaces (' ').

static String rightPad(String str, int size, char padChar)
Right pad a String with a specified character.

static String rightPad(String str, int size, String padStr)
Right pad a String with a specified String.

static String[] split(String str)
Splits the provided text into an array, using whitespace as the separator.

static String[] split(String str, char separatorChar)
Splits the provided text into an array, separator specified.

static String[] split(String str, String separatorChars)
Splits the provided text into an array, separators specified.

static String[] split(String str, String separatorChars, int max)
Splits the provided text into an array with a maximum length, separators specified.

static String[] splitByCharacterType(String str)
Splits a String by Character type as returned by java.lang.Character.getType(char).

static String[] splitByCharacterTypeCamelCase(String str)
Splits a String by Character type as returned by java.lang.Character.getType(char).

static String[] splitByWholeSeparator(String str, String separator)
Splits the provided text into an array, separator string specified.

static String[] splitByWholeSeparator(String str, String separator, int max)
Splits the provided text into an array, separator string specified.

static String[] splitByWholeSeparatorPreserveAllTokens(String str, String separator)
Splits the provided text into an array, separator string specified.

static String[] splitByWholeSeparatorPreserveAllTokens(String str, String separator, int max)
Splits the provided text into an array, separator string specified.

static String[] splitPreserveAllTokens(String str)
Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators.

static String[] splitPreserveAllTokens(String str, char separatorChar)
Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators.

static String[] splitPreserveAllTokens(String str, String separatorChars)
Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators.

static String[] splitPreserveAllTokens(String str, String separatorChars, int max)
Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.

static boolean startsWith(CharSequence str, CharSequence prefix)
Check if a CharSequence starts with a specified prefix.

static boolean startsWithAny(CharSequence string, CharSequence... searchStrings)
Check if a CharSequence starts with any of an array of specified strings.

static boolean startsWithIgnoreCase(CharSequence str, CharSequence prefix)
Case insensitive check if a CharSequence starts with a specified prefix.

static String strip(String str)
Strips whitespace from the start and end of a String.

static String strip(String str, String stripChars)
Strips any of a set of characters from the start and end of a String.

static String stripAccents(String input)
Removes diacritics (~= accents) from a string.

static String[] stripAll(String... strs)
Strips whitespace from the start and end of every String in an array.

static String[] stripAll(String[] strs, String stripChars)
Strips any of a set of characters from the start and end of every String in an array.

static String stripEnd(String str, String stripChars)
Strips any of a set of characters from the end of a String.

static String stripStart(String str, String stripChars)
Strips any of a set of characters from the start of a String.

static String stripToEmpty(String str)
Strips whitespace from the start and end of a String returning an empty String if null input.

static String stripToNull(String str)
Strips whitespace from the start and end of a String returning null if the String is empty ("") after the strip.

static String substring(String str, int start)
Gets a substring from the specified String avoiding exceptions.

static String substring(String str, int start, int end)
Gets a substring from the specified String avoiding exceptions.

static String substringAfter(String str, String separator)
Gets the substring after the first occurrence of a separator.

static String substringAfterLast(String str, String separator)
Gets the substring after the last occurrence of a separator.

static String substringBefore(String str, String separator)
Gets the substring before the first occurrence of a separator.

static String substringBeforeLast(String str, String separator)
Gets the substring before the last occurrence of a separator.

static String substringBetween(String str, String tag)
Gets the String that is nested in between two instances of the same String.

static String substringBetween(String str, String open, String close)
Gets the String that is nested in between two Strings.

static String[] substringsBetween(String str, String open, String close)
Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.

static String swapCase(String str)
Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.

static String toString(byte[] bytes, String charsetName)
Converts a byte[] to a String using the specified character encoding.

static String trim(String str)
Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

static String trimToEmpty(String str)
Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.

static String trimToNull(String str)
Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.

static String uncapitalize(String str)
Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char).

static String upperCase(String str)
Converts a String to upper case as per String.toUpperCase().

static String upperCase(String str, Locale locale)
Converts a String to upper case as per String.toUpperCase(Locale).

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

EMPTY

public static final String EMPTY

The empty String "".

Since:: 2.0
See Also:: Constant Field Values

INDEX_NOT_FOUND

public static final int INDEX_NOT_FOUND

Represents a failed index search.

Since:: 2.1
See Also:: Constant Field Values

Constructor Detail

StringUtils

public StringUtils()

StringUtils instances should NOT be constructed in standard programming. Instead, the class should be used as StringUtils.trim(" foo ");.

This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

isEmpty

public static boolean isEmpty(CharSequence cs)

Checks if a CharSequence is empty ("") or null.

 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true
 StringUtils.isEmpty(" ")       = false
 StringUtils.isEmpty("bob")     = false
 StringUtils.isEmpty("  bob  ") = false

NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if the CharSequence is empty or null
Since:: 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)

isNotEmpty

public static boolean isNotEmpty(CharSequence cs)

Checks if a CharSequence is not empty ("") and not null.

 StringUtils.isNotEmpty(null)      = false
 StringUtils.isNotEmpty("")        = false
 StringUtils.isNotEmpty(" ")       = true
 StringUtils.isNotEmpty("bob")     = true
 StringUtils.isNotEmpty("  bob  ") = true

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if the CharSequence is not empty and not null
Since:: 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)

isBlank

public static boolean isBlank(CharSequence cs)

Checks if a CharSequence is whitespace, empty ("") or null.

 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if the CharSequence is null, empty or whitespace
Since:: 2.0, 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)

isNotBlank

public static boolean isNotBlank(CharSequence cs)

Checks if a CharSequence is not empty (""), not null and not whitespace only.

 StringUtils.isNotBlank(null)      = false
 StringUtils.isNotBlank("")        = false
 StringUtils.isNotBlank(" ")       = false
 StringUtils.isNotBlank("bob")     = true
 StringUtils.isNotBlank("  bob  ") = true

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if the CharSequence is not empty and not null and not whitespace
Since:: 2.0, 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)

trim

public static String trim(String str)

Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use strip(String).

To trim your choice of characters, use the strip(String, String) methods.

 StringUtils.trim(null)          = null
 StringUtils.trim("")            = ""
 StringUtils.trim("     ")       = ""
 StringUtils.trim("abc")         = "abc"
 StringUtils.trim("    abc    ") = "abc"

Parameters:: str - the String to be trimmed, may be null
Returns:: the trimmed string, null if null String input

trimToNull

public static String trimToNull(String str)

Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToNull(String).

 StringUtils.trimToNull(null)          = null
 StringUtils.trimToNull("")            = null
 StringUtils.trimToNull("     ")       = null
 StringUtils.trimToNull("abc")         = "abc"
 StringUtils.trimToNull("    abc    ") = "abc"

Parameters:: str - the String to be trimmed, may be null
Returns:: the trimmed String, null if only chars <= 32, empty or null String input
Since:: 2.0

trimToEmpty

public static String trimToEmpty(String str)

Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToEmpty(String).

 StringUtils.trimToEmpty(null)          = ""
 StringUtils.trimToEmpty("")            = ""
 StringUtils.trimToEmpty("     ")       = ""
 StringUtils.trimToEmpty("abc")         = "abc"
 StringUtils.trimToEmpty("    abc    ") = "abc"

Parameters:: str - the String to be trimmed, may be null
Returns:: the trimmed String, or an empty String if null input
Since:: 2.0

strip

public static String strip(String str)

Strips whitespace from the start and end of a String.

This is similar to trim(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

A null input String returns null.

 StringUtils.strip(null)     = null
 StringUtils.strip("")       = ""
 StringUtils.strip("   ")    = ""
 StringUtils.strip("abc")    = "abc"
 StringUtils.strip("  abc")  = "abc"
 StringUtils.strip("abc  ")  = "abc"
 StringUtils.strip(" abc ")  = "abc"
 StringUtils.strip(" ab c ") = "ab c"

Parameters:: str - the String to remove whitespace from, may be null
Returns:: the stripped String, null if null String input

stripToNull

public static String stripToNull(String str)

Strips whitespace from the start and end of a String returning null if the String is empty ("") after the strip.

This is similar to trimToNull(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

 StringUtils.stripToNull(null)     = null
 StringUtils.stripToNull("")       = null
 StringUtils.stripToNull("   ")    = null
 StringUtils.stripToNull("abc")    = "abc"
 StringUtils.stripToNull("  abc")  = "abc"
 StringUtils.stripToNull("abc  ")  = "abc"
 StringUtils.stripToNull(" abc ")  = "abc"
 StringUtils.stripToNull(" ab c ") = "ab c"

Parameters:: str - the String to be stripped, may be null
Returns:: the stripped String, null if whitespace, empty or null String input
Since:: 2.0

stripToEmpty

public static String stripToEmpty(String str)

Strips whitespace from the start and end of a String returning an empty String if null input.

This is similar to trimToEmpty(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

 StringUtils.stripToEmpty(null)     = ""
 StringUtils.stripToEmpty("")       = ""
 StringUtils.stripToEmpty("   ")    = ""
 StringUtils.stripToEmpty("abc")    = "abc"
 StringUtils.stripToEmpty("  abc")  = "abc"
 StringUtils.stripToEmpty("abc  ")  = "abc"
 StringUtils.stripToEmpty(" abc ")  = "abc"
 StringUtils.stripToEmpty(" ab c ") = "ab c"

Parameters:: str - the String to be stripped, may be null
Returns:: the trimmed String, or an empty String if null input
Since:: 2.0

strip

public static String strip(String str,
                           String stripChars)

Strips any of a set of characters from the start and end of a String. This is similar to String.trim() but allows the characters to be stripped to be controlled.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char). Alternatively use strip(String).

 StringUtils.strip(null, *)          = null
 StringUtils.strip("", *)            = ""
 StringUtils.strip("abc", null)      = "abc"
 StringUtils.strip("  abc", null)    = "abc"
 StringUtils.strip("abc  ", null)    = "abc"
 StringUtils.strip(" abc ", null)    = "abc"
 StringUtils.strip("  abcyx", "xyz") = "  abc"

Parameters:: str - the String to remove characters from, may be null; stripChars - the characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripStart

public static String stripStart(String str,
                                String stripChars)

Strips any of a set of characters from the start of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripStart(null, *)          = null
 StringUtils.stripStart("", *)            = ""
 StringUtils.stripStart("abc", "")        = "abc"
 StringUtils.stripStart("abc", null)      = "abc"
 StringUtils.stripStart("  abc", null)    = "abc"
 StringUtils.stripStart("abc  ", null)    = "abc  "
 StringUtils.stripStart(" abc ", null)    = "abc "
 StringUtils.stripStart("yxabc  ", "xyz") = "abc  "

Parameters:: str - the String to remove characters from, may be null; stripChars - the characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripEnd

public static String stripEnd(String str,
                              String stripChars)

Strips any of a set of characters from the end of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripEnd(null, *)          = null
 StringUtils.stripEnd("", *)            = ""
 StringUtils.stripEnd("abc", "")        = "abc"
 StringUtils.stripEnd("abc", null)      = "abc"
 StringUtils.stripEnd("  abc", null)    = "  abc"
 StringUtils.stripEnd("abc  ", null)    = "abc"
 StringUtils.stripEnd(" abc ", null)    = " abc"
 StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
 StringUtils.stripEnd("120.00", ".0")   = "12"

Parameters:: str - the String to remove characters from, may be null; stripChars - the set of characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripAll

public static String[] stripAll(String... strs)

Strips whitespace from the start and end of every String in an array. Whitespace is defined by Character.isWhitespace(char).

A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored.

 StringUtils.stripAll(null)             = null
 StringUtils.stripAll([])               = []
 StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null])  = ["abc", null]

Parameters:: strs - the array to remove whitespace from, may be null
Returns:: the stripped Strings, null if null array input

stripAll

public static String[] stripAll(String[] strs,
                                String stripChars)

Strips any of a set of characters from the start and end of every String in an array.

Whitespace is defined by Character.isWhitespace(char).

A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored. A null stripChars will strip whitespace as defined by Character.isWhitespace(char).

 StringUtils.stripAll(null, *)                = null
 StringUtils.stripAll([], *)                  = []
 StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
 StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
 StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]

Parameters:: strs - the array to remove characters from, may be null; stripChars - the characters to remove, null treated as whitespace
Returns:: the stripped Strings, null if null array input

stripAccents

public static String stripAccents(String input)

Removes diacritics (~= accents) from a string. The case will not be altered.

For instance, 'à' will be replaced by 'a'.

Note that ligatures will be left as is.

This method will use the first available implementation of: Java 6's Normalizer, Java 1.3–1.5's sun.text.Normalizer

 StringUtils.stripAccents(null)                = null
 StringUtils.stripAccents("")                  = ""
 StringUtils.stripAccents("control")           = "control"
 StringUtils.stripAccents("éclair")     = "eclair"

Parameters:: input - String to be stripped
Returns:: input text with diacritics removed
Since:: 3.0

equals

public static boolean equals(CharSequence cs1,
                             CharSequence cs2)

Compares two CharSequences, returning true if they are equal.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

 StringUtils.equals(null, null)   = true
 StringUtils.equals(null, "abc")  = false
 StringUtils.equals("abc", null)  = false
 StringUtils.equals("abc", "abc") = true
 StringUtils.equals("abc", "ABC") = false

Parameters:: cs1 - the first CharSequence, may be null; cs2 - the second CharSequence, may be null
Returns:: true if the CharSequences are equal, case sensitive, or both null
Since:: 3.0 Changed signature from equals(String, String) to equals(CharSequence, CharSequence)
See Also:: String.equals(Object)

equalsIgnoreCase

public static boolean equalsIgnoreCase(CharSequence str1,
                                       CharSequence str2)

Compares two CharSequences, returning true if they are equal ignoring the case.

nulls are handled without exceptions. Two null references are considered equal. Comparison is case insensitive.

 StringUtils.equalsIgnoreCase(null, null)   = true
 StringUtils.equalsIgnoreCase(null, "abc")  = false
 StringUtils.equalsIgnoreCase("abc", null)  = false
 StringUtils.equalsIgnoreCase("abc", "abc") = true
 StringUtils.equalsIgnoreCase("abc", "ABC") = true

Parameters:: str1 - the first CharSequence, may be null; str2 - the second CharSequence, may be null
Returns:: true if the CharSequence are equal, case insensitive, or both null
Since:: 3.0 Changed signature from equalsIgnoreCase(String, String) to equalsIgnoreCase(CharSequence, CharSequence)

indexOf

public static int indexOf(CharSequence seq,
                          int searchChar)

Finds the first index within a CharSequence, handling null. This method uses String.indexOf(int, int) if possible.

A null or empty ("") CharSequence will return INDEX_NOT_FOUND (-1).

 StringUtils.indexOf(null, *)         = -1
 StringUtils.indexOf("", *)           = -1
 StringUtils.indexOf("aabaabaa", 'a') = 0
 StringUtils.indexOf("aabaabaa", 'b') = 2

Parameters:: seq - the CharSequence to check, may be null; searchChar - the character to find
Returns:: the first index of the search character, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from indexOf(String, int) to indexOf(CharSequence, int)

indexOf

public static int indexOf(CharSequence seq,
                          int searchChar,
                          int startPos)

Finds the first index within a CharSequence from a start position, handling null. This method uses String.indexOf(int, int) if possible.

A null or empty ("") CharSequence will return (INDEX_NOT_FOUND) -1. A negative start position is treated as zero. A start position greater than the string length returns -1.

 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf("", *, *)            = -1
 StringUtils.indexOf("aabaabaa", 'b', 0)  = 2
 StringUtils.indexOf("aabaabaa", 'b', 3)  = 5
 StringUtils.indexOf("aabaabaa", 'b', 9)  = -1
 StringUtils.indexOf("aabaabaa", 'b', -1) = 2

Parameters:: seq - the CharSequence to check, may be null; searchChar - the character to find; startPos - the start position, negative treated as zero
Returns:: the first index of the search character, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from indexOf(String, int, int) to indexOf(CharSequence, int, int)

indexOf

public static int indexOf(CharSequence seq,
                          CharSequence searchSeq)

Finds the first index within a CharSequence, handling null. This method uses String.indexOf(String, int) if possible.

A null CharSequence will return -1.

 StringUtils.indexOf(null, *)          = -1
 StringUtils.indexOf(*, null)          = -1
 StringUtils.indexOf("", "")           = 0
 StringUtils.indexOf("", *)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a")  = 0
 StringUtils.indexOf("aabaabaa", "b")  = 2
 StringUtils.indexOf("aabaabaa", "ab") = 1
 StringUtils.indexOf("aabaabaa", "")   = 0

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from indexOf(String, String) to indexOf(CharSequence, CharSequence)

indexOf

public static int indexOf(CharSequence seq,
                          CharSequence searchSeq,
                          int startPos)

Finds the first index within a CharSequence, handling null. This method uses String.indexOf(String, int) if possible.

A null CharSequence will return -1. A negative start position is treated as zero. An empty ("") search CharSequence always matches. A start position greater than the string length only matches an empty search CharSequence.

 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf(*, null, *)          = -1
 StringUtils.indexOf("", "", 0)           = 0
 StringUtils.indexOf("", *, 0)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a", 0)  = 0
 StringUtils.indexOf("aabaabaa", "b", 0)  = 2
 StringUtils.indexOf("aabaabaa", "ab", 0) = 1
 StringUtils.indexOf("aabaabaa", "b", 3)  = 5
 StringUtils.indexOf("aabaabaa", "b", 9)  = -1
 StringUtils.indexOf("aabaabaa", "b", -1) = 2
 StringUtils.indexOf("aabaabaa", "", 2)   = 2
 StringUtils.indexOf("abc", "", 9)        = 3

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from indexOf(String, String, int) to indexOf(CharSequence, CharSequence, int)

ordinalIndexOf

public static int ordinalIndexOf(CharSequence str,
                                 CharSequence searchStr,
                                 int ordinal)

Finds the n-th index within a CharSequence, handling null. This method uses String.indexOf(String) if possible.

A null CharSequence will return -1.

 StringUtils.ordinalIndexOf(null, *, *)          = -1
 StringUtils.ordinalIndexOf(*, null, *)          = -1
 StringUtils.ordinalIndexOf("", "", *)           = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 1)  = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 2)  = 1
 StringUtils.ordinalIndexOf("aabaabaa", "b", 1)  = 2
 StringUtils.ordinalIndexOf("aabaabaa", "b", 2)  = 5
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
 StringUtils.ordinalIndexOf("aabaabaa", "", 1)   = 0
 StringUtils.ordinalIndexOf("aabaabaa", "", 2)   = 0

Note that 'head(CharSequence str, int n)' may be implemented as:

   str.substring(0, lastOrdinalIndexOf(str, "\n", n))

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; ordinal - the n-th searchStr to find
Returns:: the n-th index of the search CharSequence, -1 (INDEX_NOT_FOUND) if no match or null string input
Since:: 2.1, 3.0 Changed signature from ordinalIndexOf(String, String, int) to ordinalIndexOf(CharSequence, CharSequence, int)

indexOfIgnoreCase

public static int indexOfIgnoreCase(CharSequence str,
                                    CharSequence searchStr)

Case in-sensitive find of the first index within a CharSequence.

 StringUtils.indexOfIgnoreCase(null, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null)          = -1
 StringUtils.indexOfIgnoreCase("", "")           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.5, 3.0 Changed signature from indexOfIgnoreCase(String, String) to indexOfIgnoreCase(CharSequence, CharSequence)

indexOfIgnoreCase

public static int indexOfIgnoreCase(CharSequence str,
                                    CharSequence searchStr,
                                    int startPos)

Case in-sensitive find of the first index within a CharSequence from the specified position.

 StringUtils.indexOfIgnoreCase(null, *, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null, *)          = -1
 StringUtils.indexOfIgnoreCase("", "", 0)           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 0)  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "AB", 0) = 1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3)  = 5
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 9)  = -1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", -1) = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "", 2)   = 2
 StringUtils.indexOfIgnoreCase("abc", "", 9)        = 3

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.5, 3.0 Changed signature from indexOfIgnoreCase(String, String, int) to indexOfIgnoreCase(CharSequence, CharSequence, int)

lastIndexOf

public static int lastIndexOf(CharSequence seq,
                              int searchChar)

Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(int) if possible.

A null or empty ("") CharSequence will return -1.

 StringUtils.lastIndexOf(null, *)         = -1
 StringUtils.lastIndexOf("", *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'a') = 7
 StringUtils.lastIndexOf("aabaabaa", 'b') = 5

Parameters:: seq - the CharSequence to check, may be null; searchChar - the character to find
Returns:: the last index of the search character, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from lastIndexOf(String, int) to lastIndexOf(CharSequence, int)

lastIndexOf

public static int lastIndexOf(CharSequence seq,
                              int searchChar,
                              int startPos)

Finds the last index within a CharSequence from a start position, handling null. This method uses String.lastIndexOf(int, int) if possible.

A null or empty ("") CharSequence will return -1. A negative start position returns -1. A start position greater than the string length searches the whole string.

 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf("", *,  *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
 StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
 StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0

Parameters:: seq - the CharSequence to check, may be null; searchChar - the character to find; startPos - the start position
Returns:: the last index of the search character, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from lastIndexOf(String, int, int) to lastIndexOf(CharSequence, int, int)

lastIndexOf

public static int lastIndexOf(CharSequence seq,
                              CharSequence searchSeq)

Finds the last index within a CharSequence, handling null. This method uses String.lastIndexOf(String) if possible.

A null CharSequence will return -1.

 StringUtils.lastIndexOf(null, *)          = -1
 StringUtils.lastIndexOf(*, null)          = -1
 StringUtils.lastIndexOf("", "")           = 0
 StringUtils.lastIndexOf("aabaabaa", "a")  = 7
 StringUtils.lastIndexOf("aabaabaa", "b")  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab") = 4
 StringUtils.lastIndexOf("aabaabaa", "")   = 8

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null
Returns:: the last index of the search String, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from lastIndexOf(String, String) to lastIndexOf(CharSequence, CharSequence)

lastOrdinalIndexOf

public static int lastOrdinalIndexOf(CharSequence str,
                                     CharSequence searchStr,
                                     int ordinal)

Finds the n-th last index within a String, handling null. This method uses String.lastIndexOf(String).

A null String will return -1.

 StringUtils.lastOrdinalIndexOf(null, *, *)          = -1
 StringUtils.lastOrdinalIndexOf(*, null, *)          = -1
 StringUtils.lastOrdinalIndexOf("", "", *)           = 0
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1)  = 7
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2)  = 6
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1)  = 5
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2)  = 2
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1)   = 8
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2)   = 8

Note that 'tail(CharSequence str, int n)' may be implemented as:

   str.substring(lastOrdinalIndexOf(str, "\n", n) + 1)

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; ordinal - the n-th last searchStr to find
Returns:: the n-th last index of the search CharSequence, -1 (INDEX_NOT_FOUND) if no match or null string input
Since:: 2.5, 3.0 Changed signature from lastOrdinalIndexOf(String, String, int) to lastOrdinalIndexOf(CharSequence, CharSequence, int)

lastIndexOf

public static int lastIndexOf(CharSequence seq,
                              CharSequence searchSeq,
                              int startPos)

Finds the first index within a CharSequence, handling null. This method uses String.lastIndexOf(String, int) if possible.

A null CharSequence will return -1. A negative start position returns -1. An empty ("") search CharSequence always matches unless the start position is negative. A start position greater than the string length searches the whole string.

 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf(*, null, *)          = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
 StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
 StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
 StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.0, 3.0 Changed signature from lastIndexOf(String, String, int) to lastIndexOf(CharSequence, CharSequence, int)

lastIndexOfIgnoreCase

public static int lastIndexOfIgnoreCase(CharSequence str,
                                        CharSequence searchStr)

Case in-sensitive find of the last index within a CharSequence.

 StringUtils.lastIndexOfIgnoreCase(null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A")  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B")  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB") = 4

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null
Returns:: the first index of the search CharSequence, -1 if no match or null string input
Since:: 2.5, 3.0 Changed signature from lastIndexOfIgnoreCase(String, String) to lastIndexOfIgnoreCase(CharSequence, CharSequence)

lastIndexOfIgnoreCase

public static int lastIndexOfIgnoreCase(CharSequence str,
                                        CharSequence searchStr,
                                        int startPos)

Case in-sensitive find of the last index within a CharSequence from the specified position.

 StringUtils.lastIndexOfIgnoreCase(null, *, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 8)  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 8)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB", 8) = 4
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 9)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", -1) = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 0)  = -1

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null; startPos - the start position
Returns:: the first index of the search CharSequence, -1 if no match or null input
Since:: 2.5, 3.0 Changed signature from lastIndexOfIgnoreCase(String, String, int) to lastIndexOfIgnoreCase(CharSequence, CharSequence, int)

contains

public static boolean contains(CharSequence seq,
                               int searchChar)

Checks if CharSequence contains a search character, handling null. This method uses String.indexOf(int) if possible.

A null or empty ("") CharSequence will return false.

 StringUtils.contains(null, *)    = false
 StringUtils.contains("", *)      = false
 StringUtils.contains("abc", 'a') = true
 StringUtils.contains("abc", 'z') = false

Parameters:: seq - the CharSequence to check, may be null; searchChar - the character to find
Returns:: true if the CharSequence contains the search character, false if not or null string input
Since:: 2.0, 3.0 Changed signature from contains(String, int) to contains(CharSequence, int)

contains

public static boolean contains(CharSequence seq,
                               CharSequence searchSeq)

Checks if CharSequence contains a search CharSequence, handling null. This method uses String.indexOf(String) if possible.

A null CharSequence will return false.

 StringUtils.contains(null, *)     = false
 StringUtils.contains(*, null)     = false
 StringUtils.contains("", "")      = true
 StringUtils.contains("abc", "")   = true
 StringUtils.contains("abc", "a")  = true
 StringUtils.contains("abc", "z")  = false

Parameters:: seq - the CharSequence to check, may be null; searchSeq - the CharSequence to find, may be null
Returns:: true if the CharSequence contains the search CharSequence, false if not or null string input
Since:: 2.0, 3.0 Changed signature from contains(String, String) to contains(CharSequence, CharSequence)

containsIgnoreCase

public static boolean containsIgnoreCase(CharSequence str,
                                         CharSequence searchStr)

Checks if CharSequence contains a search CharSequence irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).

A null CharSequence will return false.

 StringUtils.contains(null, *) = false
 StringUtils.contains(*, null) = false
 StringUtils.contains("", "") = true
 StringUtils.contains("abc", "") = true
 StringUtils.contains("abc", "a") = true
 StringUtils.contains("abc", "z") = false
 StringUtils.contains("abc", "A") = true
 StringUtils.contains("abc", "Z") = false

Parameters:: str - the CharSequence to check, may be null; searchStr - the CharSequence to find, may be null
Returns:: true if the CharSequence contains the search CharSequence irrespective of case or false if not or null string input
Since:: 3.0 Changed signature from containsIgnoreCase(String, String) to containsIgnoreCase(CharSequence, CharSequence)

containsWhitespace

public static boolean containsWhitespace(CharSequence seq)

Check whether the given CharSequence contains any whitespace characters.

Parameters:: seq - the CharSequence to check (may be null)
Returns:: true if the CharSequence is not empty and contains at least 1 whitespace character
Since:: 3.0
See Also:: Character.isWhitespace(char)

indexOfAny

public static int indexOfAny(CharSequence cs,
                             char... searchChars)

Search a CharSequence to find the first index of any character in the given set of characters.

A null String will return -1. A null or zero length search array will return -1.

 StringUtils.indexOfAny(null, *)                = -1
 StringUtils.indexOfAny("", *)                  = -1
 StringUtils.indexOfAny(*, null)                = -1
 StringUtils.indexOfAny(*, [])                  = -1
 StringUtils.indexOfAny("zzabyycdxx",['z','a']) = 0
 StringUtils.indexOfAny("zzabyycdxx",['b','y']) = 3
 StringUtils.indexOfAny("aba", ['z'])           = -1

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAny(String, char[]) to indexOfAny(CharSequence, char...)

indexOfAny

public static int indexOfAny(CharSequence cs,
                             String searchChars)

Search a CharSequence to find the first index of any character in the given set of characters.

A null String will return -1. A null search string will return -1.

 StringUtils.indexOfAny(null, *)            = -1
 StringUtils.indexOfAny("", *)              = -1
 StringUtils.indexOfAny(*, null)            = -1
 StringUtils.indexOfAny(*, "")              = -1
 StringUtils.indexOfAny("zzabyycdxx", "za") = 0
 StringUtils.indexOfAny("zzabyycdxx", "by") = 3
 StringUtils.indexOfAny("aba","z")          = -1

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAny(String, String) to indexOfAny(CharSequence, String)

containsAny

public static boolean containsAny(CharSequence cs,
                                  char... searchChars)

Checks if the CharSequence contains any character in the given set of characters.

A null CharSequence will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)                = false
 StringUtils.containsAny("", *)                  = false
 StringUtils.containsAny(*, null)                = false
 StringUtils.containsAny(*, [])                  = false
 StringUtils.containsAny("zzabyycdxx",['z','a']) = true
 StringUtils.containsAny("zzabyycdxx",['b','y']) = true
 StringUtils.containsAny("aba", ['z'])           = false

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the true if any of the chars are found, false if no match or null input
Since:: 2.4, 3.0 Changed signature from containsAny(String, char[]) to containsAny(CharSequence, char...)

containsAny

public static boolean containsAny(CharSequence cs,
                                  CharSequence searchChars)

Checks if the CharSequence contains any character in the given set of characters.

A null CharSequence will return false. A null search CharSequence will return false.

 StringUtils.containsAny(null, *)            = false
 StringUtils.containsAny("", *)              = false
 StringUtils.containsAny(*, null)            = false
 StringUtils.containsAny(*, "")              = false
 StringUtils.containsAny("zzabyycdxx", "za") = true
 StringUtils.containsAny("zzabyycdxx", "by") = true
 StringUtils.containsAny("aba","z")          = false

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the true if any of the chars are found, false if no match or null input
Since:: 2.4, 3.0 Changed signature from containsAny(String, String) to containsAny(CharSequence, CharSequence)

indexOfAnyBut

public static int indexOfAnyBut(CharSequence cs,
                                char... searchChars)

Searches a CharSequence to find the first index of any character not in the given set of characters.

A null CharSequence will return -1. A null or zero length search array will return -1.

 StringUtils.indexOfAnyBut(null, *)                              = -1
 StringUtils.indexOfAnyBut("", *)                                = -1
 StringUtils.indexOfAnyBut(*, null)                              = -1
 StringUtils.indexOfAnyBut(*, [])                                = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", new char[] {'z', 'a'} ) = 3
 StringUtils.indexOfAnyBut("aba", new char[] {'z'} )             = 0
 StringUtils.indexOfAnyBut("aba", new char[] {'a', 'b'} )        = -1

Parameters:: cs - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAnyBut(String, char[]) to indexOfAnyBut(CharSequence, char...)

indexOfAnyBut

public static int indexOfAnyBut(CharSequence seq,
                                CharSequence searchChars)

Search a CharSequence to find the first index of any character not in the given set of characters.

A null CharSequence will return -1. A null or empty search string will return -1.

 StringUtils.indexOfAnyBut(null, *)            = -1
 StringUtils.indexOfAnyBut("", *)              = -1
 StringUtils.indexOfAnyBut(*, null)            = -1
 StringUtils.indexOfAnyBut(*, "")              = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
 StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
 StringUtils.indexOfAnyBut("aba","ab")         = -1

Parameters:: seq - the CharSequence to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0, 3.0 Changed signature from indexOfAnyBut(String, String) to indexOfAnyBut(CharSequence, CharSequence)

containsOnly

public static boolean containsOnly(CharSequence cs,
                                   char... valid)

Checks if the CharSequence contains only certain characters.

A null CharSequence will return false. A null valid character array will return false. An empty CharSequence (length()=0) always returns true.

 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", '')      = false
 StringUtils.containsOnly("abab", 'abc') = true
 StringUtils.containsOnly("ab1", 'abc')  = false
 StringUtils.containsOnly("abz", 'abc')  = false

Parameters:: cs - the String to check, may be null; valid - an array of valid chars, may be null
Returns:: true if it only contains valid chars and is non-null
Since:: 3.0 Changed signature from containsOnly(String, char[]) to containsOnly(CharSequence, char...)

containsOnly

public static boolean containsOnly(CharSequence cs,
                                   String validChars)

Checks if the CharSequence contains only certain characters.

A null CharSequence will return false. A null valid character String will return false. An empty String (length()=0) always returns true.

 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", "")      = false
 StringUtils.containsOnly("abab", "abc") = true
 StringUtils.containsOnly("ab1", "abc")  = false
 StringUtils.containsOnly("abz", "abc")  = false

Parameters:: cs - the CharSequence to check, may be null; validChars - a String of valid chars, may be null
Returns:: true if it only contains valid chars and is non-null
Since:: 2.0, 3.0 Changed signature from containsOnly(String, String) to containsOnly(CharSequence, String)

containsNone

public static boolean containsNone(CharSequence cs,
                                   char... searchChars)

Checks that the CharSequence does not contain certain characters.

A null CharSequence will return true. A null invalid character array will return true. An empty CharSequence (length()=0) always returns true.

 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", '')      = true
 StringUtils.containsNone("abab", 'xyz') = true
 StringUtils.containsNone("ab1", 'xyz')  = true
 StringUtils.containsNone("abz", 'xyz')  = false

Parameters:: cs - the CharSequence to check, may be null; searchChars - an array of invalid chars, may be null
Returns:: true if it contains none of the invalid chars, or is null
Since:: 2.0, 3.0 Changed signature from containsNone(String, char[]) to containsNone(CharSequence, char...)

containsNone

public static boolean containsNone(CharSequence cs,
                                   String invalidChars)

Checks that the CharSequence does not contain certain characters.

A null CharSequence will return true. A null invalid character array will return true. An empty String ("") always returns true.

 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", "")      = true
 StringUtils.containsNone("abab", "xyz") = true
 StringUtils.containsNone("ab1", "xyz")  = true
 StringUtils.containsNone("abz", "xyz")  = false

Parameters:: cs - the CharSequence to check, may be null; invalidChars - a String of invalid chars, may be null
Returns:: true if it contains none of the invalid chars, or is null
Since:: 2.0, 3.0 Changed signature from containsNone(String, String) to containsNone(CharSequence, String)

indexOfAny

public static int indexOfAny(CharSequence str,
                             CharSequence... searchStrs)

Find the first index of any of a set of potential substrings.

A null CharSequence will return -1. A null or zero length search array will return -1. A null search array entry will be ignored, but a search array containing "" will return 0 if str is not null. This method uses String.indexOf(String) if possible.

 StringUtils.indexOfAny(null, *)                     = -1
 StringUtils.indexOfAny(*, null)                     = -1
 StringUtils.indexOfAny(*, [])                       = -1
 StringUtils.indexOfAny("zzabyycdxx", ["ab","cd"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["cd","ab"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["mn","op"])   = -1
 StringUtils.indexOfAny("zzabyycdxx", ["zab","aby"]) = 1
 StringUtils.indexOfAny("zzabyycdxx", [""])          = 0
 StringUtils.indexOfAny("", [""])                    = 0
 StringUtils.indexOfAny("", ["a"])                   = -1

Parameters:: str - the CharSequence to check, may be null; searchStrs - the CharSequences to search for, may be null
Returns:: the first index of any of the searchStrs in str, -1 if no match
Since:: 3.0 Changed signature from indexOfAny(String, String[]) to indexOfAny(CharSequence, CharSequence...)

lastIndexOfAny

public static int lastIndexOfAny(CharSequence str,
                                 CharSequence... searchStrs)

Find the latest index of any of a set of potential substrings.

A null CharSequence will return -1. A null search array will return -1. A null or zero length search array entry will be ignored, but a search array containing "" will return the length of str if str is not null. This method uses String.indexOf(String) if possible

 StringUtils.lastIndexOfAny(null, *)                   = -1
 StringUtils.lastIndexOfAny(*, null)                   = -1
 StringUtils.lastIndexOfAny(*, [])                     = -1
 StringUtils.lastIndexOfAny(*, [null])                 = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["ab","cd"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["cd","ab"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn",""])   = 10

Parameters:: str - the CharSequence to check, may be null; searchStrs - the CharSequences to search for, may be null
Returns:: the last index of any of the CharSequences, -1 if no match
Since:: 3.0 Changed signature from lastIndexOfAny(String, String[]) to lastIndexOfAny(CharSequence, CharSequence)

substring

public static String substring(String str,
                               int start)

Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start n characters from the end of the String.

A null String will return null. An empty ("") String will return "".

 StringUtils.substring(null, *)   = null
 StringUtils.substring("", *)     = ""
 StringUtils.substring("abc", 0)  = "abc"
 StringUtils.substring("abc", 2)  = "c"
 StringUtils.substring("abc", 4)  = ""
 StringUtils.substring("abc", -2) = "bc"
 StringUtils.substring("abc", -4) = "abc"

Parameters:: str - the String to get the substring from, may be null; start - the position to start from, negative means count back from the end of the String by this many characters
Returns:: substring from start position, null if null String input

substring

public static String substring(String str,
                               int start,
                               int end)

Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start/end n characters from the end of the String.

The returned substring starts with the character in the start position and ends before the end position. All position counting is zero-based -- i.e., to start at the beginning of the string use start = 0. Negative start and end positions can be used to specify offsets relative to the end of the String.

If start is not strictly to the left of end, "" is returned.

 StringUtils.substring(null, *, *)    = null
 StringUtils.substring("", * ,  *)    = "";
 StringUtils.substring("abc", 0, 2)   = "ab"
 StringUtils.substring("abc", 2, 0)   = ""
 StringUtils.substring("abc", 2, 4)   = "c"
 StringUtils.substring("abc", 4, 6)   = ""
 StringUtils.substring("abc", 2, 2)   = ""
 StringUtils.substring("abc", -2, -1) = "b"
 StringUtils.substring("abc", -4, 2)  = "ab"

Parameters:: str - the String to get the substring from, may be null; start - the position to start from, negative means count back from the end of the String by this many characters; end - the position to end at (exclusive), negative means count back from the end of the String by this many characters
Returns:: substring from start position to end position, null if null String input

left

public static String left(String str,
                          int len)

Gets the leftmost len characters of a String.

If len characters are not available, or the String is null, the String will be returned without an exception. An empty String is returned if len is negative.

 StringUtils.left(null, *)    = null
 StringUtils.left(*, -ve)     = ""
 StringUtils.left("", *)      = ""
 StringUtils.left("abc", 0)   = ""
 StringUtils.left("abc", 2)   = "ab"
 StringUtils.left("abc", 4)   = "abc"

Parameters:: str - the String to get the leftmost characters from, may be null; len - the length of the required String
Returns:: the leftmost characters, null if null String input

right

public static String right(String str,
                           int len)

Gets the rightmost len characters of a String.

If len characters are not available, or the String is null, the String will be returned without an an exception. An empty String is returned if len is negative.

 StringUtils.right(null, *)    = null
 StringUtils.right(*, -ve)     = ""
 StringUtils.right("", *)      = ""
 StringUtils.right("abc", 0)   = ""
 StringUtils.right("abc", 2)   = "bc"
 StringUtils.right("abc", 4)   = "abc"

Parameters:: str - the String to get the rightmost characters from, may be null; len - the length of the required String
Returns:: the rightmost characters, null if null String input

mid

public static String mid(String str,
                         int pos,
                         int len)

Gets len characters from the middle of a String.

If len characters are not available, the remainder of the String will be returned without an exception. If the String is null, null will be returned. An empty String is returned if len is negative or exceeds the length of str.

 StringUtils.mid(null, *, *)    = null
 StringUtils.mid(*, *, -ve)     = ""
 StringUtils.mid("", 0, *)      = ""
 StringUtils.mid("abc", 0, 2)   = "ab"
 StringUtils.mid("abc", 0, 4)   = "abc"
 StringUtils.mid("abc", 2, 4)   = "c"
 StringUtils.mid("abc", 4, 2)   = ""
 StringUtils.mid("abc", -2, 2)  = "ab"

Parameters:: str - the String to get the characters from, may be null; pos - the position to start from, negative treated as zero; len - the length of the required String
Returns:: the middle characters, null if null String input

substringBefore

public static String substringBefore(String str,
                                     String separator)

Gets the substring before the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the input string.

If nothing is found, the string input is returned.

 StringUtils.substringBefore(null, *)      = null
 StringUtils.substringBefore("", *)        = ""
 StringUtils.substringBefore("abc", "a")   = ""
 StringUtils.substringBefore("abcba", "b") = "a"
 StringUtils.substringBefore("abc", "c")   = "ab"
 StringUtils.substringBefore("abc", "d")   = "abc"
 StringUtils.substringBefore("abc", "")    = ""
 StringUtils.substringBefore("abc", null)  = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring before the first occurrence of the separator, null if null String input
Since:: 2.0

substringAfter

public static String substringAfter(String str,
                                    String separator)

Gets the substring after the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfter(null, *)      = null
 StringUtils.substringAfter("", *)        = ""
 StringUtils.substringAfter(*, null)      = ""
 StringUtils.substringAfter("abc", "a")   = "bc"
 StringUtils.substringAfter("abcba", "b") = "cba"
 StringUtils.substringAfter("abc", "c")   = ""
 StringUtils.substringAfter("abc", "d")   = ""
 StringUtils.substringAfter("abc", "")    = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the first occurrence of the separator, null if null String input
Since:: 2.0

substringBeforeLast

public static String substringBeforeLast(String str,
                                         String separator)

Gets the substring before the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the input string.

If nothing is found, the string input is returned.

 StringUtils.substringBeforeLast(null, *)      = null
 StringUtils.substringBeforeLast("", *)        = ""
 StringUtils.substringBeforeLast("abcba", "b") = "abc"
 StringUtils.substringBeforeLast("abc", "c")   = "ab"
 StringUtils.substringBeforeLast("a", "a")     = ""
 StringUtils.substringBeforeLast("a", "z")     = "a"
 StringUtils.substringBeforeLast("a", null)    = "a"
 StringUtils.substringBeforeLast("a", "")      = "a"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring before the last occurrence of the separator, null if null String input
Since:: 2.0

substringAfterLast

public static String substringAfterLast(String str,
                                        String separator)

Gets the substring after the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfterLast(null, *)      = null
 StringUtils.substringAfterLast("", *)        = ""
 StringUtils.substringAfterLast(*, "")        = ""
 StringUtils.substringAfterLast(*, null)      = ""
 StringUtils.substringAfterLast("abc", "a")   = "bc"
 StringUtils.substringAfterLast("abcba", "b") = "a"
 StringUtils.substringAfterLast("abc", "c")   = ""
 StringUtils.substringAfterLast("a", "a")     = ""
 StringUtils.substringAfterLast("a", "z")     = ""

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the last occurrence of the separator, null if null String input
Since:: 2.0

substringBetween

public static String substringBetween(String str,
                                      String tag)

Gets the String that is nested in between two instances of the same String.

A null input String returns null. A null tag returns null.

 StringUtils.substringBetween(null, *)            = null
 StringUtils.substringBetween("", "")             = ""
 StringUtils.substringBetween("", "tag")          = null
 StringUtils.substringBetween("tagabctag", null)  = null
 StringUtils.substringBetween("tagabctag", "")    = ""
 StringUtils.substringBetween("tagabctag", "tag") = "abc"

Parameters:: str - the String containing the substring, may be null; tag - the String before and after the substring, may be null
Returns:: the substring, null if no match
Since:: 2.0

substringBetween

public static String substringBetween(String str,
                                      String open,
                                      String close)

Gets the String that is nested in between two Strings. Only the first match is returned.

A null input String returns null. A null open/close returns null (no match). An empty ("") open and close returns an empty string.

 StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
 StringUtils.substringBetween(null, *, *)          = null
 StringUtils.substringBetween(*, null, *)          = null
 StringUtils.substringBetween(*, *, null)          = null
 StringUtils.substringBetween("", "", "")          = ""
 StringUtils.substringBetween("", "", "]")         = null
 StringUtils.substringBetween("", "[", "]")        = null
 StringUtils.substringBetween("yabcz", "", "")     = ""
 StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
 StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"

Parameters:: str - the String containing the substring, may be null; open - the String before the substring, may be null; close - the String after the substring, may be null
Returns:: the substring, null if no match
Since:: 2.0

substringsBetween

public static String[] substringsBetween(String str,
                                         String open,
                                         String close)

Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.

A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns null (no match).

 StringUtils.substringsBetween("[a][b][c]", "[", "]") = ["a","b","c"]
 StringUtils.substringsBetween(null, *, *)            = null
 StringUtils.substringsBetween(*, null, *)            = null
 StringUtils.substringsBetween(*, *, null)            = null
 StringUtils.substringsBetween("", "[", "]")          = []

Parameters:: str - the String containing the substrings, null returns null, empty returns empty; open - the String identifying the start of the substring, empty returns null; close - the String identifying the end of the substring, empty returns null
Returns:: a String Array of substrings, or null if no match
Since:: 2.3

split

public static String[] split(String str)

Splits the provided text into an array, using whitespace as the separator. Whitespace is defined by Character.isWhitespace(char).

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null.

 StringUtils.split(null)       = null
 StringUtils.split("")         = []
 StringUtils.split("abc def")  = ["abc", "def"]
 StringUtils.split("abc  def") = ["abc", "def"]
 StringUtils.split(" abc ")    = ["abc"]

Parameters:: str - the String to parse, may be null
Returns:: an array of parsed Strings, null if null String input

split

public static String[] split(String str,
                             char separatorChar)

Splits the provided text into an array, separator specified. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null.

 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
 StringUtils.split("a:b:c", '.')    = ["a:b:c"]
 StringUtils.split("a b c", ' ')    = ["a", "b", "c"]

Parameters:: str - the String to parse, may be null; separatorChar - the character used as the delimiter
Returns:: an array of parsed Strings, null if null String input
Since:: 2.0

split

public static String[] split(String str,
                             String separatorChars)

Splits the provided text into an array, separators specified. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separatorChars splits on whitespace.

 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("abc def", null) = ["abc", "def"]
 StringUtils.split("abc def", " ")  = ["abc", "def"]
 StringUtils.split("abc  def", " ") = ["abc", "def"]
 StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input

split

public static String[] split(String str,
                             String separatorChars,
                             int max)

Splits the provided text into an array with a maximum length, separators specified.

The separator is not included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separatorChars splits on whitespace.

If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).

 StringUtils.split(null, *, *)            = null
 StringUtils.split("", *, *)              = []
 StringUtils.split("ab de fg", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.split("ab   de fg", null, 0) = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace; max - the maximum number of elements to include in the array. A zero or negative value implies no limit
Returns:: an array of parsed Strings, null if null String input

splitByWholeSeparator

public static String[] splitByWholeSeparator(String str,
                                             String separator)

Splits the provided text into an array, separator string specified.

The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparator(null, *)               = null
 StringUtils.splitByWholeSeparator("", *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String was input

splitByWholeSeparator

public static String[] splitByWholeSeparator(String str,
                                             String separator,
                                             int max)

Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparator(null, *, *)               = null
 StringUtils.splitByWholeSeparator("", *, *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null, 0)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace; max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
Returns:: an array of parsed Strings, null if null String was input

splitByWholeSeparatorPreserveAllTokens

public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                                              String separator)

Splits the provided text into an array, separator string specified.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String was input
Since:: 2.4

splitByWholeSeparatorPreserveAllTokens

public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                                              String separator,
                                                              int max)

Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *, *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null, 0)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace; max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
Returns:: an array of parsed Strings, null if null String was input
Since:: 2.4

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str)

Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer. Whitespace is defined by Character.isWhitespace(char).

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null.

 StringUtils.splitPreserveAllTokens(null)       = null
 StringUtils.splitPreserveAllTokens("")         = []
 StringUtils.splitPreserveAllTokens("abc def")  = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def") = ["abc", "", "def"]
 StringUtils.splitPreserveAllTokens(" abc ")    = ["", "abc", ""]

Parameters:: str - the String to parse, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              char separatorChar)

Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null.

 StringUtils.splitPreserveAllTokens(null, *)         = null
 StringUtils.splitPreserveAllTokens("", *)           = []
 StringUtils.splitPreserveAllTokens("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a..b.c", '.')   = ["a", "", "b", "c"]
 StringUtils.splitPreserveAllTokens("a:b:c", '.')    = ["a:b:c"]
 StringUtils.splitPreserveAllTokens("a\tb\nc", null) = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c", ' ')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c ", ' ')   = ["a", "b", "c", ""]
 StringUtils.splitPreserveAllTokens("a b c  ", ' ')   = ["a", "b", "c", "", ""]
 StringUtils.splitPreserveAllTokens(" a b c", ' ')   = ["", a", "b", "c"]
 StringUtils.splitPreserveAllTokens("  a b c", ' ')  = ["", "", a", "b", "c"]
 StringUtils.splitPreserveAllTokens(" a b c ", ' ')  = ["", a", "b", "c", ""]

Parameters:: str - the String to parse, may be null; separatorChar - the character used as the delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              String separatorChars)

Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separatorChars splits on whitespace.

 StringUtils.splitPreserveAllTokens(null, *)           = null
 StringUtils.splitPreserveAllTokens("", *)             = []
 StringUtils.splitPreserveAllTokens("abc def", null)   = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc def", " ")    = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def", " ")   = ["abc", "", def"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":")   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":")  = ["ab", "cd", "ef", ""]
 StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
 StringUtils.splitPreserveAllTokens("ab::cd:ef", ":")  = ["ab", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef", ":")     = ["", cd", "ef"]
 StringUtils.splitPreserveAllTokens("::cd:ef", ":")    = ["", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef:", ":")    = ["", cd", "ef", ""]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              String separatorChars,
                                              int max)

Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. Adjacent separators are treated as one separator.

A null input String returns null. A null separatorChars splits on whitespace.

If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).

 StringUtils.splitPreserveAllTokens(null, *, *)            = null
 StringUtils.splitPreserveAllTokens("", *, *)              = []
 StringUtils.splitPreserveAllTokens("ab de fg", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 0) = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 2) = ["ab", "  de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 3) = ["ab", "", " de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 4) = ["ab", "", "", "de fg"]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace; max - the maximum number of elements to include in the array. A zero or negative value implies no limit
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitByCharacterType

public static String[] splitByCharacterType(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens.

 StringUtils.splitByCharacterType(null)         = null
 StringUtils.splitByCharacterType("")           = []
 StringUtils.splitByCharacterType("ab de fg")   = ["ab", " ", "de", " ", "fg"]
 StringUtils.splitByCharacterType("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
 StringUtils.splitByCharacterType("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
 StringUtils.splitByCharacterType("number5")    = ["number", "5"]
 StringUtils.splitByCharacterType("fooBar")     = ["foo", "B", "ar"]
 StringUtils.splitByCharacterType("foo200Bar")  = ["foo", "200", "B", "ar"]
 StringUtils.splitByCharacterType("ASFRules")   = ["ASFR", "ules"]

Parameters:: str - the String to split, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.4

splitByCharacterTypeCamelCase

public static String[] splitByCharacterTypeCamelCase(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens, with the following exception: the character of type Character.UPPERCASE_LETTER, if any, immediately preceding a token of type Character.LOWERCASE_LETTER will belong to the following token rather than to the preceding, if any, Character.UPPERCASE_LETTER token.

 StringUtils.splitByCharacterTypeCamelCase(null)         = null
 StringUtils.splitByCharacterTypeCamelCase("")           = []
 StringUtils.splitByCharacterTypeCamelCase("ab de fg")   = ["ab", " ", "de", " ", "fg"]
 StringUtils.splitByCharacterTypeCamelCase("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
 StringUtils.splitByCharacterTypeCamelCase("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
 StringUtils.splitByCharacterTypeCamelCase("number5")    = ["number", "5"]
 StringUtils.splitByCharacterTypeCamelCase("fooBar")     = ["foo", "Bar"]
 StringUtils.splitByCharacterTypeCamelCase("foo200Bar")  = ["foo", "200", "Bar"]
 StringUtils.splitByCharacterTypeCamelCase("ASFRules")   = ["ASF", "Rules"]

Parameters:: str - the String to split, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.4

join

public static <T> String join(T... elements)

Joins the elements of the provided array into a single String containing the provided list of elements.

No separator is added to the joined String. Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null)            = null
 StringUtils.join([])              = ""
 StringUtils.join([null])          = ""
 StringUtils.join(["a", "b", "c"]) = "abc"
 StringUtils.join([null, "", "a"]) = "a"

Type Parameters:: T - the specific type of values to join together
Parameters:: elements - the values to join together, may be null
Returns:: the joined String, null if null array input
Since:: 2.0, 3.0 Changed signature to use varargs

join

public static String join(Object[] array,
                          char separator)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"

Parameters:: array - the array of values to join together, may be null; separator - the separator character to use
Returns:: the joined String, null if null array input
Since:: 2.0

join

public static String join(Object[] array,
                          char separator,
                          int startIndex,
                          int endIndex)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"

Parameters:: array - the array of values to join together, may be null; separator - the separator character to use; startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array; endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
Returns:: the joined String, null if null array input
Since:: 2.0

join

public static String join(Object[] array,
                          String separator)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = ""
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = ",,a"

Parameters:: array - the array of values to join together, may be null; separator - the separator character to use, null treated as ""
Returns:: the joined String, null if null array input

join

public static String join(Object[] array,
                          String separator,
                          int startIndex,
                          int endIndex)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = ""
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = ",,a"

Parameters:: array - the array of values to join together, may be null; separator - the separator character to use, null treated as ""; startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array; endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array
Returns:: the joined String, null if null array input

join

public static String join(Iterator<?> iterator,
                          char separator)

Joins the elements of the provided Iterator into a single String containing the provided elements.

No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

See the examples here: join(Object[],char).

Parameters:: iterator - the Iterator of values to join together, may be null; separator - the separator character to use
Returns:: the joined String, null if null iterator input
Since:: 2.0

join

public static String join(Iterator<?> iterator,
                          String separator)

Joins the elements of the provided Iterator into a single String containing the provided elements.

No delimiter is added before or after the list. A null separator is the same as an empty String ("").

See the examples here: join(Object[],String).

Parameters:: iterator - the Iterator of values to join together, may be null; separator - the separator character to use, null treated as ""
Returns:: the joined String, null if null iterator input

join

public static String join(Iterable<?> iterable,
                          char separator)

Joins the elements of the provided Iterable into a single String containing the provided elements.

No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

See the examples here: join(Object[],char).

Parameters:: iterable - the Iterable providing the values to join together, may be null; separator - the separator character to use
Returns:: the joined String, null if null iterator input
Since:: 2.3

join

public static String join(Iterable<?> iterable,
                          String separator)

Joins the elements of the provided Iterable into a single String containing the provided elements.

No delimiter is added before or after the list. A null separator is the same as an empty String ("").

See the examples here: join(Object[],String).

Parameters:: iterable - the Iterable providing the values to join together, may be null; separator - the separator character to use, null treated as ""
Returns:: the joined String, null if null iterator input
Since:: 2.3

deleteWhitespace

public static String deleteWhitespace(String str)

Deletes all whitespaces from a String as defined by Character.isWhitespace(char).

 StringUtils.deleteWhitespace(null)         = null
 StringUtils.deleteWhitespace("")           = ""
 StringUtils.deleteWhitespace("abc")        = "abc"
 StringUtils.deleteWhitespace("   ab  c  ") = "abc"

Parameters:: str - the String to delete whitespace from, may be null
Returns:: the String without whitespaces, null if null String input

removeStart

public static String removeStart(String str,
                                 String remove)

Removes a substring only if it is at the beginning of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeStart(null, *)      = null
 StringUtils.removeStart("", *)        = ""
 StringUtils.removeStart(*, null)      = *
 StringUtils.removeStart("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStart("domain.com", "www.")       = "domain.com"
 StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStart("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

removeStartIgnoreCase

public static String removeStartIgnoreCase(String str,
                                           String remove)

Case insensitive removal of a substring if it is at the beginning of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeStartIgnoreCase(null, *)      = null
 StringUtils.removeStartIgnoreCase("", *)        = ""
 StringUtils.removeStartIgnoreCase(*, null)      = *
 StringUtils.removeStartIgnoreCase("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "WWW.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("domain.com", "www.")       = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStartIgnoreCase("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.4

removeEnd

public static String removeEnd(String str,
                               String remove)

Removes a substring only if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEnd(null, *)      = null
 StringUtils.removeEnd("", *)        = ""
 StringUtils.removeEnd(*, null)      = *
 StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEnd("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

removeEndIgnoreCase

public static String removeEndIgnoreCase(String str,
                                         String remove)

Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEndIgnoreCase(null, *)      = null
 StringUtils.removeEndIgnoreCase("", *)        = ""
 StringUtils.removeEndIgnoreCase(*, null)      = *
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEndIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEndIgnoreCase("abc", "")    = "abc"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".COM") = "www.domain")
 StringUtils.removeEndIgnoreCase("www.domain.COM", ".com") = "www.domain")

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.4

remove

public static String remove(String str,
                            String remove)

Removes all occurrences of a substring from within the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.

 StringUtils.remove(null, *)        = null
 StringUtils.remove("", *)          = ""
 StringUtils.remove(*, null)        = *
 StringUtils.remove(*, "")          = *
 StringUtils.remove("queued", "ue") = "qd"
 StringUtils.remove("queued", "zz") = "queued"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

remove

public static String remove(String str,
                            char remove)

Removes all occurrences of a character from within the source string.

A null source string will return null. An empty ("") source string will return the empty string.

 StringUtils.remove(null, *)       = null
 StringUtils.remove("", *)         = ""
 StringUtils.remove("queued", 'u') = "qeed"
 StringUtils.remove("queued", 'z') = "queued"

Parameters:: str - the source String to search, may be null; remove - the char to search for and remove, may be null
Returns:: the substring with the char removed if found, null if null String input
Since:: 2.1

replaceOnce

public static String replaceOnce(String text,
                                 String searchString,
                                 String replacement)

Replaces a String with another String inside a larger String, once.

A null reference passed to this method is a no-op.

 StringUtils.replaceOnce(null, *, *)        = null
 StringUtils.replaceOnce("", *, *)          = ""
 StringUtils.replaceOnce("any", null, *)    = "any"
 StringUtils.replaceOnce("any", *, null)    = "any"
 StringUtils.replaceOnce("any", "", *)      = "any"
 StringUtils.replaceOnce("aba", "a", null)  = "aba"
 StringUtils.replaceOnce("aba", "a", "")    = "ba"
 StringUtils.replaceOnce("aba", "a", "z")   = "zba"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace with, may be null
Returns:: the text with any replacements processed, null if null String input
See Also:: replace(String text, String searchString, String replacement, int max)

replace

public static String replace(String text,
                             String searchString,
                             String replacement)

Replaces all occurrences of a String within another String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *)        = null
 StringUtils.replace("", *, *)          = ""
 StringUtils.replace("any", null, *)    = "any"
 StringUtils.replace("any", *, null)    = "any"
 StringUtils.replace("any", "", *)      = "any"
 StringUtils.replace("aba", "a", null)  = "aba"
 StringUtils.replace("aba", "a", "")    = "b"
 StringUtils.replace("aba", "a", "z")   = "zbz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace it with, may be null
Returns:: the text with any replacements processed, null if null String input
See Also:: replace(String text, String searchString, String replacement, int max)

replace

public static String replace(String text,
                             String searchString,
                             String replacement,
                             int max)

Replaces a String with another String inside a larger String, for the first max values of the search String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *, *)         = null
 StringUtils.replace("", *, *, *)           = ""
 StringUtils.replace("any", null, *, *)     = "any"
 StringUtils.replace("any", *, null, *)     = "any"
 StringUtils.replace("any", "", *, *)       = "any"
 StringUtils.replace("any", *, *, 0)        = "any"
 StringUtils.replace("abaa", "a", null, -1) = "abaa"
 StringUtils.replace("abaa", "a", "", -1)   = "b"
 StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
 StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
 StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
 StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace it with, may be null; max - maximum number of values to replace, or -1 if no maximum
Returns:: the text with any replacements processed, null if null String input

replaceEach

public static String replaceEach(String text,
                                 String[] searchList,
                                 String[] replacementList)

Replaces all occurrences of Strings within another String.

A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.

  StringUtils.replaceEach(null, *, *)        = null
  StringUtils.replaceEach("", *, *)          = ""
  StringUtils.replaceEach("aba", null, null) = "aba"
  StringUtils.replaceEach("aba", new String[0], null) = "aba"
  StringUtils.replaceEach("aba", null, new String[0]) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
  (example of how it does not repeat)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"

Parameters:: text - text to search and replace in, no-op if null; searchList - the Strings to search for, no-op if null; replacementList - the Strings to replace them with, no-op if null
Returns:: the text with any replacements processed, null if null String input
Throws:: IllegalArgumentException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
Since:: 2.4

replaceEachRepeatedly

public static String replaceEachRepeatedly(String text,
                                           String[] searchList,
                                           String[] replacementList)

Replaces all occurrences of Strings within another String.

A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored.

  StringUtils.replaceEach(null, *, *, *) = null
  StringUtils.replaceEach("", *, *, *) = ""
  StringUtils.replaceEach("aba", null, null, *) = "aba"
  StringUtils.replaceEach("aba", new String[0], null, *) = "aba"
  StringUtils.replaceEach("aba", null, new String[0], *) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null, *) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *) = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *) = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *) = "wcte"
  (example of how it repeats)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false) = "dcte"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true) = "tcte"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, true) = IllegalStateException
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, false) = "dcabe"

Parameters:: text - text to search and replace in, no-op if null; searchList - the Strings to search for, no-op if null; replacementList - the Strings to replace them with, no-op if null
Returns:: the text with any replacements processed, null if null String input
Throws:: IllegalStateException - if the search is repeating and there is an endless loop due to outputs of one being inputs to another; IllegalArgumentException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
Since:: 2.4

replaceChars

public static String replaceChars(String str,
                                  char searchChar,
                                  char replaceChar)

Replaces all occurrences of a character in a String with another. This is a null-safe version of String.replace(char, char).

A null string input returns null. An empty ("") string input returns an empty string.

 StringUtils.replaceChars(null, *, *)        = null
 StringUtils.replaceChars("", *, *)          = ""
 StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
 StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"

Parameters:: str - String to replace characters in, may be null; searchChar - the character to search for, may be null; replaceChar - the character to replace, may be null
Returns:: modified String, null if null string input
Since:: 2.0

replaceChars

public static String replaceChars(String str,
                                  String searchChars,
                                  String replaceChars)

Replaces multiple characters in a String in one go. This method can also be used to delete characters.

For example:
replaceChars("hello", "ho", "jy") = jelly.

A null string input returns null. An empty ("") string input returns an empty string. A null or empty set of search characters returns the input string.

The length of the search characters should normally equal the length of the replace characters. If the search characters is longer, then the extra search characters are deleted. If the search characters is shorter, then the extra replace characters are ignored.

 StringUtils.replaceChars(null, *, *)           = null
 StringUtils.replaceChars("", *, *)             = ""
 StringUtils.replaceChars("abc", null, *)       = "abc"
 StringUtils.replaceChars("abc", "", *)         = "abc"
 StringUtils.replaceChars("abc", "b", null)     = "ac"
 StringUtils.replaceChars("abc", "b", "")       = "ac"
 StringUtils.replaceChars("abcba", "bc", "yz")  = "ayzya"
 StringUtils.replaceChars("abcba", "bc", "y")   = "ayya"
 StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"

Parameters:: str - String to replace characters in, may be null; searchChars - a set of characters to search for, may be null; replaceChars - a set of characters to replace, may be null
Returns:: modified String, null if null string input
Since:: 2.0

overlay

public static String overlay(String str,
                             String overlay,
                             int start,
                             int end)

Overlays part of a String with another String.

A null string input returns null. A negative index is treated as zero. An index greater than the string length is treated as the string length. The start index is always the smaller of the two indices.

 StringUtils.overlay(null, *, *, *)            = null
 StringUtils.overlay("", "abc", 0, 0)          = "abc"
 StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
 StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
 StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
 StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
 StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
 StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
 StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"

Parameters:: str - the String to do overlaying in, may be null; overlay - the String to overlay, may be null; start - the position to start overlaying at; end - the position to stop overlaying before
Returns:: overlayed String, null if null String input
Since:: 2.0

chomp

public static String chomp(String str)

Removes one newline from end of a String if it's there, otherwise leave it alone. A newline is "\n", "\r", or "\r\n".

NOTE: This method changed in 2.0. It now more closely matches Perl chomp.

 StringUtils.chomp(null)          = null
 StringUtils.chomp("")            = ""
 StringUtils.chomp("abc \r")      = "abc "
 StringUtils.chomp("abc\n")       = "abc"
 StringUtils.chomp("abc\r\n")     = "abc"
 StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"
 StringUtils.chomp("abc\n\r")     = "abc\n"
 StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"
 StringUtils.chomp("\r")          = ""
 StringUtils.chomp("\n")          = ""
 StringUtils.chomp("\r\n")        = ""

Parameters:: str - the String to chomp a newline from, may be null
Returns:: String without newline, null if null String input

chomp

@Deprecated
public static String chomp(String str,
                                      String separator)

Deprecated. This feature will be removed in Lang 4.0, use removeEnd(String, String) instead

Removes separator from the end of str if it's there, otherwise leave it alone.

NOTE: This method changed in version 2.0. It now more closely matches Perl chomp. For the previous behavior, use substringBeforeLast(String, String). This method uses String.endsWith(String).

 StringUtils.chomp(null, *)         = null
 StringUtils.chomp("", *)           = ""
 StringUtils.chomp("foobar", "bar") = "foo"
 StringUtils.chomp("foobar", "baz") = "foobar"
 StringUtils.chomp("foo", "foo")    = ""
 StringUtils.chomp("foo ", "foo")   = "foo "
 StringUtils.chomp(" foo", "foo")   = " "
 StringUtils.chomp("foo", "foooo")  = "foo"
 StringUtils.chomp("foo", "")       = "foo"
 StringUtils.chomp("foo", null)     = "foo"

Parameters:: str - the String to chomp from, may be null; separator - separator String, may be null
Returns:: String without trailing separator, null if null String input

chop

public static String chop(String str)

Remove the last character from a String.

If the String ends in \r\n, then remove both of them.

 StringUtils.chop(null)          = null
 StringUtils.chop("")            = ""
 StringUtils.chop("abc \r")      = "abc "
 StringUtils.chop("abc\n")       = "abc"
 StringUtils.chop("abc\r\n")     = "abc"
 StringUtils.chop("abc")         = "ab"
 StringUtils.chop("abc\nabc")    = "abc\nab"
 StringUtils.chop("a")           = ""
 StringUtils.chop("\r")          = ""
 StringUtils.chop("\n")          = ""
 StringUtils.chop("\r\n")        = ""

Parameters:: str - the String to chop last character from, may be null
Returns:: String without last character, null if null String input

repeat

public static String repeat(String str,
                            int repeat)

Repeat a String repeat times to form a new String.

 StringUtils.repeat(null, 2) = null
 StringUtils.repeat("", 0)   = ""
 StringUtils.repeat("", 2)   = ""
 StringUtils.repeat("a", 3)  = "aaa"
 StringUtils.repeat("ab", 2) = "abab"
 StringUtils.repeat("a", -2) = ""

Parameters:: str - the String to repeat, may be null; repeat - number of times to repeat str, negative treated as zero
Returns:: a new String consisting of the original String repeated, null if null String input

repeat

public static String repeat(String str,
                            String separator,
                            int repeat)

Repeat a String repeat times to form a new String, with a String separator injected each time.

 StringUtils.repeat(null, null, 2) = null
 StringUtils.repeat(null, "x", 2)  = null
 StringUtils.repeat("", null, 0)   = ""
 StringUtils.repeat("", "", 2)     = ""
 StringUtils.repeat("", "x", 3)    = "xxx"
 StringUtils.repeat("?", ", ", 3)  = "?, ?, ?"

Parameters:: str - the String to repeat, may be null; separator - the String to inject, may be null; repeat - number of times to repeat str, negative treated as zero
Returns:: a new String consisting of the original String repeated, null if null String input
Since:: 2.5

repeat

public static String repeat(char ch,
                            int repeat)

Returns padding using the specified delimiter repeated to a given length.

 StringUtils.repeat(0, 'e')  = ""
 StringUtils.repeat(3, 'e')  = "eee"
 StringUtils.repeat(-2, 'e') = ""

Note: this method doesn't not support padding with Unicode Supplementary Characters as they require a pair of chars to be represented. If you are needing to support full I18N of your applications consider using repeat(String, int) instead.

Parameters:: ch - character to repeat; repeat - number of times to repeat char, negative treated as zero
Returns:: String with repeated character
See Also:: repeat(String, int)

rightPad

public static String rightPad(String str,
                              int size)

Right pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.rightPad(null, *)   = null
 StringUtils.rightPad("", 3)     = "   "
 StringUtils.rightPad("bat", 3)  = "bat"
 StringUtils.rightPad("bat", 5)  = "bat  "
 StringUtils.rightPad("bat", 1)  = "bat"
 StringUtils.rightPad("bat", -1) = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to
Returns:: right padded String or original String if no padding is necessary, null if null String input

rightPad

public static String rightPad(String str,
                              int size,
                              char padChar)

Right pad a String with a specified character.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)     = null
 StringUtils.rightPad("", 3, 'z')     = "zzz"
 StringUtils.rightPad("bat", 3, 'z')  = "bat"
 StringUtils.rightPad("bat", 5, 'z')  = "batzz"
 StringUtils.rightPad("bat", 1, 'z')  = "bat"
 StringUtils.rightPad("bat", -1, 'z') = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padChar - the character to pad with
Returns:: right padded String or original String if no padding is necessary, null if null String input
Since:: 2.0

rightPad

public static String rightPad(String str,
                              int size,
                              String padStr)

Right pad a String with a specified String.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)      = null
 StringUtils.rightPad("", 3, "z")      = "zzz"
 StringUtils.rightPad("bat", 3, "yz")  = "bat"
 StringUtils.rightPad("bat", 5, "yz")  = "batyz"
 StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
 StringUtils.rightPad("bat", 1, "yz")  = "bat"
 StringUtils.rightPad("bat", -1, "yz") = "bat"
 StringUtils.rightPad("bat", 5, null)  = "bat  "
 StringUtils.rightPad("bat", 5, "")    = "bat  "

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padStr - the String to pad with, null or empty treated as single space
Returns:: right padded String or original String if no padding is necessary, null if null String input

leftPad

public static String leftPad(String str,
                             int size)

Left pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.leftPad(null, *)   = null
 StringUtils.leftPad("", 3)     = "   "
 StringUtils.leftPad("bat", 3)  = "bat"
 StringUtils.leftPad("bat", 5)  = "  bat"
 StringUtils.leftPad("bat", 1)  = "bat"
 StringUtils.leftPad("bat", -1) = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to
Returns:: left padded String or original String if no padding is necessary, null if null String input

leftPad

public static String leftPad(String str,
                             int size,
                             char padChar)

Left pad a String with a specified character.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)     = null
 StringUtils.leftPad("", 3, 'z')     = "zzz"
 StringUtils.leftPad("bat", 3, 'z')  = "bat"
 StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
 StringUtils.leftPad("bat", 1, 'z')  = "bat"
 StringUtils.leftPad("bat", -1, 'z') = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padChar - the character to pad with
Returns:: left padded String or original String if no padding is necessary, null if null String input
Since:: 2.0

leftPad

public static String leftPad(String str,
                             int size,
                             String padStr)

Left pad a String with a specified String.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)      = null
 StringUtils.leftPad("", 3, "z")      = "zzz"
 StringUtils.leftPad("bat", 3, "yz")  = "bat"
 StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
 StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
 StringUtils.leftPad("bat", 1, "yz")  = "bat"
 StringUtils.leftPad("bat", -1, "yz") = "bat"
 StringUtils.leftPad("bat", 5, null)  = "  bat"
 StringUtils.leftPad("bat", 5, "")    = "  bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padStr - the String to pad with, null or empty treated as single space
Returns:: left padded String or original String if no padding is necessary, null if null String input

length

public static int length(CharSequence cs)

Gets a CharSequence length or 0 if the CharSequence is null.

Parameters:: cs - a CharSequence or null
Returns:: CharSequence length or 0 if the CharSequence is null.
Since:: 2.4, 3.0 Changed signature from length(String) to length(CharSequence)

center

public static String center(String str,
                            int size)

Centers a String in a larger String of size size using the space character (' ').

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

Equivalent to center(str, size, " ").

 StringUtils.center(null, *)   = null
 StringUtils.center("", 4)     = "    "
 StringUtils.center("ab", -1)  = "ab"
 StringUtils.center("ab", 4)   = " ab "
 StringUtils.center("abcd", 2) = "abcd"
 StringUtils.center("a", 4)    = " a  "

Parameters:: str - the String to center, may be null; size - the int size of new String, negative treated as zero
Returns:: centered String, null if null String input

center

public static String center(String str,
                            int size,
                            char padChar)

Centers a String in a larger String of size size. Uses a supplied character as the value to pad the String with.

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, ' ')     = "    "
 StringUtils.center("ab", -1, ' ')  = "ab"
 StringUtils.center("ab", 4, ' ')   = " ab"
 StringUtils.center("abcd", 2, ' ') = "abcd"
 StringUtils.center("a", 4, ' ')    = " a  "
 StringUtils.center("a", 4, 'y')    = "yayy"

Parameters:: str - the String to center, may be null; size - the int size of new String, negative treated as zero; padChar - the character to pad the new String with
Returns:: centered String, null if null String input
Since:: 2.0

center

public static String center(String str,
                            int size,
                            String padStr)

Centers a String in a larger String of size size. Uses a supplied String as the value to pad the String with.

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, " ")     = "    "
 StringUtils.center("ab", -1, " ")  = "ab"
 StringUtils.center("ab", 4, " ")   = " ab"
 StringUtils.center("abcd", 2, " ") = "abcd"
 StringUtils.center("a", 4, " ")    = " a  "
 StringUtils.center("a", 4, "yz")   = "yayz"
 StringUtils.center("abc", 7, null) = "  abc  "
 StringUtils.center("abc", 7, "")   = "  abc  "

Parameters:: str - the String to center, may be null; size - the int size of new String, negative treated as zero; padStr - the String to pad the new String with, must not be null or empty
Returns:: centered String, null if null String input
Throws:: IllegalArgumentException - if padStr is null or empty

upperCase

public static String upperCase(String str)

Converts a String to upper case as per String.toUpperCase().

A null input String returns null.

 StringUtils.upperCase(null)  = null
 StringUtils.upperCase("")    = ""
 StringUtils.upperCase("aBc") = "ABC"

Note: As described in the documentation for String.toUpperCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).

Parameters:: str - the String to upper case, may be null
Returns:: the upper cased String, null if null String input

upperCase

public static String upperCase(String str,
                               Locale locale)

Converts a String to upper case as per String.toUpperCase(Locale).

A null input String returns null.

 StringUtils.upperCase(null, Locale.ENGLISH)  = null
 StringUtils.upperCase("", Locale.ENGLISH)    = ""
 StringUtils.upperCase("aBc", Locale.ENGLISH) = "ABC"

Parameters:: str - the String to upper case, may be null; locale - the locale that defines the case transformation rules, must not be null
Returns:: the upper cased String, null if null String input
Since:: 2.5

lowerCase

public static String lowerCase(String str)

Converts a String to lower case as per String.toLowerCase().

A null input String returns null.

 StringUtils.lowerCase(null)  = null
 StringUtils.lowerCase("")    = ""
 StringUtils.lowerCase("aBc") = "abc"

Note: As described in the documentation for String.toLowerCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).

Parameters:: str - the String to lower case, may be null
Returns:: the lower cased String, null if null String input

lowerCase

public static String lowerCase(String str,
                               Locale locale)

Converts a String to lower case as per String.toLowerCase(Locale).

A null input String returns null.

 StringUtils.lowerCase(null, Locale.ENGLISH)  = null
 StringUtils.lowerCase("", Locale.ENGLISH)    = ""
 StringUtils.lowerCase("aBc", Locale.ENGLISH) = "abc"

Parameters:: str - the String to lower case, may be null; locale - the locale that defines the case transformation rules, must not be null
Returns:: the lower cased String, null if null String input
Since:: 2.5

capitalize

public static String capitalize(String str)

Capitalizes a String changing the first letter to title case as per Character.toTitleCase(char). No other letters are changed.

For a word based algorithm, see WordUtils.capitalize(String). A null input String returns null.

 StringUtils.capitalize(null)  = null
 StringUtils.capitalize("")    = ""
 StringUtils.capitalize("cat") = "Cat"
 StringUtils.capitalize("cAt") = "CAt"

Parameters:: str - the String to capitalize, may be null
Returns:: the capitalized String, null if null String input
Since:: 2.0
See Also:: WordUtils.capitalize(String), uncapitalize(String)

uncapitalize

public static String uncapitalize(String str)

Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char). No other letters are changed.

For a word based algorithm, see WordUtils.uncapitalize(String). A null input String returns null.

 StringUtils.uncapitalize(null)  = null
 StringUtils.uncapitalize("")    = ""
 StringUtils.uncapitalize("Cat") = "cat"
 StringUtils.uncapitalize("CAT") = "cAT"

Parameters:: str - the String to uncapitalize, may be null
Returns:: the uncapitalized String, null if null String input
Since:: 2.0
See Also:: WordUtils.uncapitalize(String), capitalize(String)

swapCase

public static String swapCase(String str)

Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.

Upper case character converts to Lower case
Title case character converts to Lower case
Lower case character converts to Upper case

For a word based algorithm, see WordUtils.swapCase(String). A null input String returns null.

 StringUtils.swapCase(null)                 = null
 StringUtils.swapCase("")                   = ""
 StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"

NOTE: This method changed in Lang version 2.0. It no longer performs a word based algorithm. If you only use ASCII, you will notice no change. That functionality is available in org.apache.commons.lang3.text.WordUtils.

Parameters:: str - the String to swap case, may be null
Returns:: the changed String, null if null String input

countMatches

public static int countMatches(CharSequence str,
                               CharSequence sub)

Counts how many times the substring appears in the larger string.

A null or empty ("") String input returns 0.

 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", null)  = 0
 StringUtils.countMatches("abba", "")    = 0
 StringUtils.countMatches("abba", "a")   = 2
 StringUtils.countMatches("abba", "ab")  = 1
 StringUtils.countMatches("abba", "xxx") = 0

Parameters:: str - the CharSequence to check, may be null; sub - the substring to count, may be null
Returns:: the number of occurrences, 0 if either CharSequence is null
Since:: 3.0 Changed signature from countMatches(String, String) to countMatches(CharSequence, CharSequence)

isAlpha

public static boolean isAlpha(CharSequence cs)

Checks if the CharSequence contains only Unicode letters.

null will return false. An empty CharSequence (length()=0) will return false.

 StringUtils.isAlpha(null)   = false
 StringUtils.isAlpha("")     = false
 StringUtils.isAlpha("  ")   = false
 StringUtils.isAlpha("abc")  = true
 StringUtils.isAlpha("ab2c") = false
 StringUtils.isAlpha("ab-c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains letters, and is non-null
Since:: 3.0 Changed signature from isAlpha(String) to isAlpha(CharSequence), 3.0 Changed "" to return false and not true

isAlphaSpace

public static boolean isAlphaSpace(CharSequence cs)

Checks if the CharSequence contains only Unicode letters and space (' ').

null will return false An empty CharSequence (length()=0) will return true.

 StringUtils.isAlphaSpace(null)   = false
 StringUtils.isAlphaSpace("")     = true
 StringUtils.isAlphaSpace("  ")   = true
 StringUtils.isAlphaSpace("abc")  = true
 StringUtils.isAlphaSpace("ab c") = true
 StringUtils.isAlphaSpace("ab2c") = false
 StringUtils.isAlphaSpace("ab-c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains letters and space, and is non-null
Since:: 3.0 Changed signature from isAlphaSpace(String) to isAlphaSpace(CharSequence)

isAlphanumeric

public static boolean isAlphanumeric(CharSequence cs)

Checks if the CharSequence contains only Unicode letters or digits.

null will return false. An empty CharSequence (length()=0) will return false.

 StringUtils.isAlphanumeric(null)   = false
 StringUtils.isAlphanumeric("")     = false
 StringUtils.isAlphanumeric("  ")   = false
 StringUtils.isAlphanumeric("abc")  = true
 StringUtils.isAlphanumeric("ab c") = false
 StringUtils.isAlphanumeric("ab2c") = true
 StringUtils.isAlphanumeric("ab-c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains letters or digits, and is non-null
Since:: 3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence), 3.0 Changed "" to return false and not true

isAlphanumericSpace

public static boolean isAlphanumericSpace(CharSequence cs)

Checks if the CharSequence contains only Unicode letters, digits or space (' ').

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isAlphanumericSpace(null)   = false
 StringUtils.isAlphanumericSpace("")     = true
 StringUtils.isAlphanumericSpace("  ")   = true
 StringUtils.isAlphanumericSpace("abc")  = true
 StringUtils.isAlphanumericSpace("ab c") = true
 StringUtils.isAlphanumericSpace("ab2c") = true
 StringUtils.isAlphanumericSpace("ab-c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains letters, digits or space, and is non-null
Since:: 3.0 Changed signature from isAlphanumericSpace(String) to isAlphanumericSpace(CharSequence)

isAsciiPrintable

public static boolean isAsciiPrintable(CharSequence cs)

Checks if the CharSequence contains only ASCII printable characters.

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isAsciiPrintable(null)     = false
 StringUtils.isAsciiPrintable("")       = true
 StringUtils.isAsciiPrintable(" ")      = true
 StringUtils.isAsciiPrintable("Ceki")   = true
 StringUtils.isAsciiPrintable("ab2c")   = true
 StringUtils.isAsciiPrintable("!ab-c~") = true
 StringUtils.isAsciiPrintable(" ") = true
 StringUtils.isAsciiPrintable("!") = true
 StringUtils.isAsciiPrintable("~") = true
 StringUtils.isAsciiPrintable("") = false
 StringUtils.isAsciiPrintable("Ceki Gülcü") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if every character is in the range 32 thru 126
Since:: 2.1, 3.0 Changed signature from isAsciiPrintable(String) to isAsciiPrintable(CharSequence)

isNumeric

public static boolean isNumeric(CharSequence cs)

Checks if the CharSequence contains only Unicode digits. A decimal point is not a Unicode digit and returns false.

null will return false. An empty CharSequence (length()=0) will return false.

 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = false
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains digits, and is non-null
Since:: 3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence), 3.0 Changed "" to return false and not true

isNumericSpace

public static boolean isNumericSpace(CharSequence cs)

Checks if the CharSequence contains only Unicode digits or space (' '). A decimal point is not a Unicode digit and returns false.

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isNumericSpace(null)   = false
 StringUtils.isNumericSpace("")     = true
 StringUtils.isNumericSpace("  ")   = true
 StringUtils.isNumericSpace("123")  = true
 StringUtils.isNumericSpace("12 3") = true
 StringUtils.isNumericSpace("ab2c") = false
 StringUtils.isNumericSpace("12-3") = false
 StringUtils.isNumericSpace("12.3") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains digits or space, and is non-null
Since:: 3.0 Changed signature from isNumericSpace(String) to isNumericSpace(CharSequence)

isWhitespace

public static boolean isWhitespace(CharSequence cs)

Checks if the CharSequence contains only whitespace.

null will return false. An empty CharSequence (length()=0) will return true.

 StringUtils.isWhitespace(null)   = false
 StringUtils.isWhitespace("")     = true
 StringUtils.isWhitespace("  ")   = true
 StringUtils.isWhitespace("abc")  = false
 StringUtils.isWhitespace("ab2c") = false
 StringUtils.isWhitespace("ab-c") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains whitespace, and is non-null
Since:: 2.0, 3.0 Changed signature from isWhitespace(String) to isWhitespace(CharSequence)

isAllLowerCase

public static boolean isAllLowerCase(CharSequence cs)

Checks if the CharSequence contains only lowercase characters.

null will return false. An empty CharSequence (length()=0) will return false.

 StringUtils.isAllLowerCase(null)   = false
 StringUtils.isAllLowerCase("")     = false
 StringUtils.isAllLowerCase("  ")   = false
 StringUtils.isAllLowerCase("abc")  = true
 StringUtils.isAllLowerCase("abC") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains lowercase characters, and is non-null
Since:: 2.5, 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence)

isAllUpperCase

public static boolean isAllUpperCase(CharSequence cs)

Checks if the CharSequence contains only uppercase characters.

null will return false. An empty String (length()=0) will return false.

 StringUtils.isAllUpperCase(null)   = false
 StringUtils.isAllUpperCase("")     = false
 StringUtils.isAllUpperCase("  ")   = false
 StringUtils.isAllUpperCase("ABC")  = true
 StringUtils.isAllUpperCase("aBC") = false

Parameters:: cs - the CharSequence to check, may be null
Returns:: true if only contains uppercase characters, and is non-null
Since:: 2.5, 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence)

defaultString

public static String defaultString(String str)

Returns either the passed in String, or if the String is null, an empty String ("").

 StringUtils.defaultString(null)  = ""
 StringUtils.defaultString("")    = ""
 StringUtils.defaultString("bat") = "bat"

Parameters:: str - the String to check, may be null
Returns:: the passed in String, or the empty String if it was null
See Also:: ObjectUtils.toString(Object), String.valueOf(Object)

defaultString

public static String defaultString(String str,
                                   String defaultStr)

Returns either the passed in String, or if the String is null, the value of defaultStr.

 StringUtils.defaultString(null, "NULL")  = "NULL"
 StringUtils.defaultString("", "NULL")    = ""
 StringUtils.defaultString("bat", "NULL") = "bat"

Parameters:: str - the String to check, may be null; defaultStr - the default String to return if the input is null, may be null
Returns:: the passed in String, or the default if it was null
See Also:: ObjectUtils.toString(Object,String), String.valueOf(Object)

defaultIfBlank

public static <T extends CharSequence> T defaultIfBlank(T str,
                                                        T defaultStr)

Returns either the passed in CharSequence, or if the CharSequence is whitespace, empty ("") or null, the value of defaultStr.

 StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
 StringUtils.defaultIfBlank("", "NULL")    = "NULL"
 StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
 StringUtils.defaultIfBlank("bat", "NULL") = "bat"
 StringUtils.defaultIfBlank("", null)      = null

Type Parameters:: T - the specific kind of CharSequence
Parameters:: str - the CharSequence to check, may be null; defaultStr - the default CharSequence to return if the input is whitespace, empty ("") or null, may be null
Returns:: the passed in CharSequence, or the default
See Also:: defaultString(String, String)

defaultIfEmpty

public static <T extends CharSequence> T defaultIfEmpty(T str,
                                                        T defaultStr)

Returns either the passed in CharSequence, or if the CharSequence is empty or null, the value of defaultStr.

 StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
 StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
 StringUtils.defaultIfEmpty(" ", "NULL")   = " "
 StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
 StringUtils.defaultIfEmpty("", null)      = null

Type Parameters:: T - the specific kind of CharSequence
Parameters:: str - the CharSequence to check, may be null; defaultStr - the default CharSequence to return if the input is empty ("") or null, may be null
Returns:: the passed in CharSequence, or the default
See Also:: defaultString(String, String)

reverse

public static String reverse(String str)

Reverses a String as per StringBuilder.reverse().

A null String returns null.

 StringUtils.reverse(null)  = null
 StringUtils.reverse("")    = ""
 StringUtils.reverse("bat") = "tab"

Parameters:: str - the String to reverse, may be null
Returns:: the reversed String, null if null String input

reverseDelimited

public static String reverseDelimited(String str,
                                      char separatorChar)

Reverses a String that is delimited by a specific character.

The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is '.').

 StringUtils.reverseDelimited(null, *)      = null
 StringUtils.reverseDelimited("", *)        = ""
 StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
 StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"

Parameters:: str - the String to reverse, may be null; separatorChar - the separator character to use
Returns:: the reversed String, null if null String input
Since:: 2.0

abbreviate

public static String abbreviate(String str,
                                int maxWidth)

Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."

Specifically:

If str is less than maxWidth characters long, return it.
Else abbreviate it to (substring(str, 0, max-3) + "...").
If maxWidth is less than 4, throw an IllegalArgumentException.
In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, *)      = null
 StringUtils.abbreviate("", 4)        = ""
 StringUtils.abbreviate("abcdefg", 6) = "abc..."
 StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 4) = "a..."
 StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException

Parameters:: str - the String to check, may be null; maxWidth - maximum length of result String, must be at least 4
Returns:: abbreviated String, null if null String input
Throws:: IllegalArgumentException - if the width is too small
Since:: 2.0

abbreviate

public static String abbreviate(String str,
                                int offset,
                                int maxWidth)

Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "...is the time for..."

Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear somewhere in the result.

In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, *, *)                = null
 StringUtils.abbreviate("", 0, 4)                  = ""
 StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
 StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
 StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
 StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException

Parameters:: str - the String to check, may be null; offset - left edge of source String; maxWidth - maximum length of result String, must be at least 4
Returns:: abbreviated String, null if null String input
Throws:: IllegalArgumentException - if the width is too small
Since:: 2.0

abbreviateMiddle

public static String abbreviateMiddle(String str,
                                      String middle,
                                      int length)

Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.

This abbreviation only occurs if the following criteria is met:

Neither the String for abbreviation nor the replacement String are null or empty
The length to truncate to is less than the length of the supplied String
The length to truncate to is greater than 0
The abbreviated String will have enough room for the length supplied replacement String and the first and last characters of the supplied String for abbreviation

Otherwise, the returned String will be the same as the supplied String for abbreviation.

 StringUtils.abbreviateMiddle(null, null, 0)      = null
 StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"
 StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"

Parameters:: str - the String to abbreviate, may be null; middle - the String to replace the middle characters with, may be null; length - the length to abbreviate str to.
Returns:: the abbreviated String if the above criteria is met, or the original String supplied for abbreviation.
Since:: 2.5

difference

public static String difference(String str1,
                                String str2)

Compares two Strings, and returns the portion where they differ. (More precisely, return the remainder of the second String, starting from where it's different from the first.)

For example, difference("i am a machine", "i am a robot") -> "robot".

 StringUtils.difference(null, null) = null
 StringUtils.difference("", "") = ""
 StringUtils.difference("", "abc") = "abc"
 StringUtils.difference("abc", "") = ""
 StringUtils.difference("abc", "abc") = ""
 StringUtils.difference("ab", "abxyz") = "xyz"
 StringUtils.difference("abcde", "abxyz") = "xyz"
 StringUtils.difference("abcde", "xyz") = "xyz"

Parameters:: str1 - the first String, may be null; str2 - the second String, may be null
Returns:: the portion of str2 where it differs from str1; returns the empty String if they are equal
Since:: 2.0

indexOfDifference

public static int indexOfDifference(CharSequence cs1,
                                    CharSequence cs2)

Compares two CharSequences, and returns the index at which the CharSequences begin to differ.

For example, indexOfDifference("i am a machine", "i am a robot") -> 7

 StringUtils.indexOfDifference(null, null) = -1
 StringUtils.indexOfDifference("", "") = -1
 StringUtils.indexOfDifference("", "abc") = 0
 StringUtils.indexOfDifference("abc", "") = 0
 StringUtils.indexOfDifference("abc", "abc") = -1
 StringUtils.indexOfDifference("ab", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "xyz") = 0

Parameters:: cs1 - the first CharSequence, may be null; cs2 - the second CharSequence, may be null
Returns:: the index where cs1 and cs2 begin to differ; -1 if they are equal
Since:: 2.0, 3.0 Changed signature from indexOfDifference(String, String) to indexOfDifference(CharSequence, CharSequence)

indexOfDifference

public static int indexOfDifference(CharSequence... css)

Compares all CharSequences in an array and returns the index at which the CharSequences begin to differ.

For example, indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7

 StringUtils.indexOfDifference(null) = -1
 StringUtils.indexOfDifference(new String[] {}) = -1
 StringUtils.indexOfDifference(new String[] {"abc"}) = -1
 StringUtils.indexOfDifference(new String[] {null, null}) = -1
 StringUtils.indexOfDifference(new String[] {"", ""}) = -1
 StringUtils.indexOfDifference(new String[] {"", null}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0
 StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1
 StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1
 StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0
 StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0
 StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7

Parameters:: css - array of CharSequences, entries may be null
Returns:: the index where the strings begin to differ; -1 if they are all equal
Since:: 2.4, 3.0 Changed signature from indexOfDifference(String...) to indexOfDifference(CharSequence...)

getCommonPrefix

public static String getCommonPrefix(String... strs)

Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.

For example, getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "

 StringUtils.getCommonPrefix(null) = ""
 StringUtils.getCommonPrefix(new String[] {}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {"", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"", null}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"
 StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""
 StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""
 StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "

Parameters:: strs - array of String objects, entries may be null
Returns:: the initial sequence of characters that are common to all Strings in the array; empty String if the array is null, the elements are all null or if there is no common prefix.
Since:: 2.4

getLevenshteinDistance

public static int getLevenshteinDistance(CharSequence s,
                                         CharSequence t)

Find the Levenshtein distance between two Strings.

This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

The previous implementation of the Levenshtein distance algorithm was from http://www.merriampark.com/ld.htm

Chas Emerick has written an implementation in Java, which avoids an OutOfMemoryError which can occur when my Java implementation is used with very large strings.
This implementation of the Levenshtein distance algorithm is from http://www.merriampark.com/ldjava.htm

 StringUtils.getLevenshteinDistance(null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance("","")               = 0
 StringUtils.getLevenshteinDistance("","a")              = 1
 StringUtils.getLevenshteinDistance("aaapppp", "")       = 7
 StringUtils.getLevenshteinDistance("frog", "fog")       = 1
 StringUtils.getLevenshteinDistance("fly", "ant")        = 3
 StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
 StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
 StringUtils.getLevenshteinDistance("hello", "hallo")    = 1

Parameters:: s - the first String, must not be null; t - the second String, must not be null
Returns:: result distance
Throws:: IllegalArgumentException - if either String input null
Since:: 3.0 Changed signature from getLevenshteinDistance(String, String) to getLevenshteinDistance(CharSequence, CharSequence)

getLevenshteinDistance

public static int getLevenshteinDistance(CharSequence s,
                                         CharSequence t,
                                         int threshold)

Find the Levenshtein distance between two Strings if it's less than or equal to a given threshold.

This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

This implementation follows from Algorithms on Strings, Trees and Sequences by Dan Gusfield and Chas Emerick's implementation of the Levenshtein distance algorithm from http://www.merriampark.com/ld.htm

 StringUtils.getLevenshteinDistance(null, *, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, *, -1)               = IllegalArgumentException
 StringUtils.getLevenshteinDistance("","", 0)               = 0
 StringUtils.getLevenshteinDistance("aaapppp", "", 8)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 7)       = 7
 StringUtils.getLevenshteinDistance("aaapppp", "", 6))      = -1
 StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7
 StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1
 StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1

Parameters:: s - the first String, must not be null; t - the second String, must not be null; threshold - the target threshold, must not be negative
Returns:: result distance, or -1 if the distance would be greater than the threshold
Throws:: IllegalArgumentException - if either String input null or negative threshold

startsWith

public static boolean startsWith(CharSequence str,
                                 CharSequence prefix)

Check if a CharSequence starts with a specified prefix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

 StringUtils.startsWith(null, null)      = true
 StringUtils.startsWith(null, "abc")     = false
 StringUtils.startsWith("abcdef", null)  = false
 StringUtils.startsWith("abcdef", "abc") = true
 StringUtils.startsWith("ABCDEF", "abc") = false

Parameters:: str - the CharSequence to check, may be null; prefix - the prefix to find, may be null
Returns:: true if the CharSequence starts with the prefix, case sensitive, or both null
Since:: 2.4, 3.0 Changed signature from startsWith(String, String) to startsWith(CharSequence, CharSequence)
See Also:: String.startsWith(String)

startsWithIgnoreCase

public static boolean startsWithIgnoreCase(CharSequence str,
                                           CharSequence prefix)

Case insensitive check if a CharSequence starts with a specified prefix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

 StringUtils.startsWithIgnoreCase(null, null)      = true
 StringUtils.startsWithIgnoreCase(null, "abc")     = false
 StringUtils.startsWithIgnoreCase("abcdef", null)  = false
 StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
 StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true

Parameters:: str - the CharSequence to check, may be null; prefix - the prefix to find, may be null
Returns:: true if the CharSequence starts with the prefix, case insensitive, or both null
Since:: 2.4, 3.0 Changed signature from startsWithIgnoreCase(String, String) to startsWithIgnoreCase(CharSequence, CharSequence)
See Also:: String.startsWith(String)

startsWithAny

public static boolean startsWithAny(CharSequence string,
                                    CharSequence... searchStrings)

Check if a CharSequence starts with any of an array of specified strings.

 StringUtils.startsWithAny(null, null)      = false
 StringUtils.startsWithAny(null, new String[] {"abc"})  = false
 StringUtils.startsWithAny("abcxyz", null)     = false
 StringUtils.startsWithAny("abcxyz", new String[] {""}) = false
 StringUtils.startsWithAny("abcxyz", new String[] {"abc"}) = true
 StringUtils.startsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true

Parameters:: string - the CharSequence to check, may be null; searchStrings - the CharSequences to find, may be null or empty
Returns:: true if the CharSequence starts with any of the the prefixes, case insensitive, or both null
Since:: 2.5, 3.0 Changed signature from startsWithAny(String, String[]) to startsWithAny(CharSequence, CharSequence...)

endsWith

public static boolean endsWith(CharSequence str,
                               CharSequence suffix)

Check if a CharSequence ends with a specified suffix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

 StringUtils.endsWith(null, null)      = true
 StringUtils.endsWith(null, "def")     = false
 StringUtils.endsWith("abcdef", null)  = false
 StringUtils.endsWith("abcdef", "def") = true
 StringUtils.endsWith("ABCDEF", "def") = false
 StringUtils.endsWith("ABCDEF", "cde") = false

Parameters:: str - the CharSequence to check, may be null; suffix - the suffix to find, may be null
Returns:: true if the CharSequence ends with the suffix, case sensitive, or both null
Since:: 2.4, 3.0 Changed signature from endsWith(String, String) to endsWith(CharSequence, CharSequence)
See Also:: String.endsWith(String)

endsWithIgnoreCase

public static boolean endsWithIgnoreCase(CharSequence str,
                                         CharSequence suffix)

Case insensitive check if a CharSequence ends with a specified suffix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

 StringUtils.endsWithIgnoreCase(null, null)      = true
 StringUtils.endsWithIgnoreCase(null, "def")     = false
 StringUtils.endsWithIgnoreCase("abcdef", null)  = false
 StringUtils.endsWithIgnoreCase("abcdef", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false

Parameters:: str - the CharSequence to check, may be null; suffix - the suffix to find, may be null
Returns:: true if the CharSequence ends with the suffix, case insensitive, or both null
Since:: 2.4, 3.0 Changed signature from endsWithIgnoreCase(String, String) to endsWithIgnoreCase(CharSequence, CharSequence)
See Also:: String.endsWith(String)

normalizeSpace

public static String normalizeSpace(String str)

The function returns the argument string with whitespace normalized by using trim(String) to remove leading and trailing whitespace and then replacing sequences of whitespace characters by a single space.

In XML Whitespace characters are the same as those allowed by the S production, which is S ::= (#x20 | #x9 | #xD | #xA)+

Java's regexp pattern \s defines whitespace as [ \t\n\x0B\f\r]

For reference:

\x0B = vertical tab
\f = #xC = form feed
#x20 = space
#x9 = \t
#xA = \n
#xD = \r

The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also normalize. Additionally trim(String) removes control characters (char <= 32) from both ends of this String.

Parameters:: str - the source String to normalize whitespaces from, may be null
Returns:: the modified string with whitespace normalized, null if null String input
Since:: 3.0
See Also:: Pattern, trim(String), http://www.w3.org/TR/xpath/#function-normalize-space

endsWithAny

public static boolean endsWithAny(CharSequence string,
                                  CharSequence... searchStrings)

Check if a CharSequence ends with any of an array of specified strings.

 StringUtils.endsWithAny(null, null)      = false
 StringUtils.endsWithAny(null, new String[] {"abc"})  = false
 StringUtils.endsWithAny("abcxyz", null)     = false
 StringUtils.endsWithAny("abcxyz", new String[] {""}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true

Parameters:: string - the CharSequence to check, may be null; searchStrings - the CharSequences to find, may be null or empty
Returns:: true if the CharSequence ends with any of the the prefixes, case insensitive, or both null
Since:: 3.0

toString

public static String toString(byte[] bytes,
                              String charsetName)
                       throws UnsupportedEncodingException

Converts a byte[] to a String using the specified character encoding.

Parameters:: bytes - the byte array to read from; charsetName - the encoding to use, if null then use the platform default
Returns:: a new String
Throws:: UnsupportedEncodingException - If the named charset is not supported; NullPointerException - if the input is null
Since:: 3.1

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