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org.apache.commons.lang
Class CharUtils

java.lang.Object
  extended byorg.apache.commons.lang.CharUtils
public class CharUtils
extends java.lang.Object

Operations on char primitives and Character objects.

This class tries to handle null input gracefully. An exception will not be thrown for a null input. Each method documents its behaviour in more detail.

Since:
2.1
Version:
$Id: CharUtils.java 437554 2006-08-28 06:21:41Z bayard $
Author:
Stephen Colebourne

Field Summary
static char CR
           carriage return CR ('\r').
static char LF
           linefeed LF ('\n').
 
Constructor Summary
CharUtils()
          CharUtils instances should NOT be constructed in standard programming.
 
Method Summary
static boolean isAscii(char ch)
          Checks whether the character is ASCII 7 bit.
static boolean isAsciiAlpha(char ch)
          Checks whether the character is ASCII 7 bit alphabetic.
static boolean isAsciiAlphaLower(char ch)
          Checks whether the character is ASCII 7 bit alphabetic lower case.
static boolean isAsciiAlphanumeric(char ch)
          Checks whether the character is ASCII 7 bit numeric.
static boolean isAsciiAlphaUpper(char ch)
          Checks whether the character is ASCII 7 bit alphabetic upper case.
static boolean isAsciiControl(char ch)
          Checks whether the character is ASCII 7 bit control.
static boolean isAsciiNumeric(char ch)
          Checks whether the character is ASCII 7 bit numeric.
static boolean isAsciiPrintable(char ch)
          Checks whether the character is ASCII 7 bit printable.
static char toChar(java.lang.Character ch)
          Converts the Character to a char throwing an exception for null.
static char toChar(java.lang.Character ch, char defaultValue)
          Converts the Character to a char handling null.
static char toChar(java.lang.String str)
          Converts the String to a char using the first character, throwing an exception on empty Strings.
static char toChar(java.lang.String str, char defaultValue)
          Converts the String to a char using the first character, defaulting the value on empty Strings.
static java.lang.Character toCharacterObject(char ch)
          Converts the character to a Character.
static java.lang.Character toCharacterObject(java.lang.String str)
          Converts the String to a Character using the first character, returning null for empty Strings.
static int toIntValue(char ch)
          Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
static int toIntValue(java.lang.Character ch)
          Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
static int toIntValue(java.lang.Character ch, int defaultValue)
          Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
static int toIntValue(char ch, int defaultValue)
          Converts the character to the Integer it represents, throwing an exception if the character is not numeric.
static java.lang.String toString(char ch)
          Converts the character to a String that contains the one character.
static java.lang.String toString(java.lang.Character ch)
          Converts the character to a String that contains the one character.
static java.lang.String unicodeEscaped(char ch)
          Converts the string to the unicode format ' '.
static java.lang.String unicodeEscaped(java.lang.Character ch)
          Converts the string to the unicode format ' '.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LF

public static final char LF
linefeed LF ('\n').

Since:
2.2
See Also:
JLF: Escape Sequences for Character and String Literals, Constant Field Values

CR

public static final char CR
carriage return CR ('\r').

Since:
2.2
See Also:
JLF: Escape Sequences for Character and String Literals, Constant Field Values
Constructor Detail

CharUtils

public CharUtils()

CharUtils instances should NOT be constructed in standard programming. Instead, the class should be used as CharUtils.toString('c');.

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

Method Detail

toCharacterObject

public static java.lang.Character toCharacterObject(char ch)

Converts the character to a Character.

For ASCII 7 bit characters, this uses a cache that will return the same Character object each time.

   CharUtils.toCharacterObject(' ')  = ' '
   CharUtils.toCharacterObject('A')  = 'A'

Parameters:
ch - the character to convert
Returns:
a Character of the specified character

toCharacterObject

public static java.lang.Character toCharacterObject(java.lang.String str)

Converts the String to a Character using the first character, returning null for empty Strings.

For ASCII 7 bit characters, this uses a cache that will return the same Character object each time.

   CharUtils.toCharacterObject(null) = null
   CharUtils.toCharacterObject("")   = null
   CharUtils.toCharacterObject("A")  = 'A'
   CharUtils.toCharacterObject("BA") = 'B'

Parameters:
str - the character to convert
Returns:
the Character value of the first letter of the String

toChar

public static char toChar(java.lang.Character ch)

Converts the Character to a char throwing an exception for null.

   CharUtils.toChar(null) = IllegalArgumentException
   CharUtils.toChar(' ')  = ' '
   CharUtils.toChar('A')  = 'A'

Parameters:
ch - the character to convert
Returns:
the char value of the Character
Throws:
java.lang.IllegalArgumentException - if the Character is null

toChar

public static char toChar(java.lang.Character ch,
                          char defaultValue)

Converts the Character to a char handling null.

   CharUtils.toChar(null, 'X') = 'X'
   CharUtils.toChar(' ', 'X')  = ' '
   CharUtils.toChar('A', 'X')  = 'A'

Parameters:
ch - the character to convert
defaultValue - the value to use if the Character is null
Returns:
the char value of the Character or the default if null

toChar

public static char toChar(java.lang.String str)

Converts the String to a char using the first character, throwing an exception on empty Strings.

   CharUtils.toChar(null) = IllegalArgumentException
   CharUtils.toChar("")   = IllegalArgumentException
   CharUtils.toChar("A")  = 'A'
   CharUtils.toChar("BA") = 'B'

Parameters:
str - the character to convert
Returns:
the char value of the first letter of the String
Throws:
java.lang.IllegalArgumentException - if the String is empty

toChar

public static char toChar(java.lang.String str,
                          char defaultValue)

Converts the String to a char using the first character, defaulting the value on empty Strings.

   CharUtils.toChar(null, 'X') = 'X'
   CharUtils.toChar("", 'X')   = 'X'
   CharUtils.toChar("A", 'X')  = 'A'
   CharUtils.toChar("BA", 'X') = 'B'

Parameters:
str - the character to convert
defaultValue - the value to use if the Character is null
Returns:
the char value of the first letter of the String or the default if null

toIntValue

public static int toIntValue(char ch)

Converts the character to the Integer it represents, throwing an exception if the character is not numeric.

This method coverts the char '1' to the int 1 and so on.

   CharUtils.toIntValue('3')  = 3
   CharUtils.toIntValue('A')  = IllegalArgumentException

Parameters:
ch - the character to convert
Returns:
the int value of the character
Throws:
java.lang.IllegalArgumentException - if the character is not ASCII numeric

toIntValue

public static int toIntValue(char ch,
                             int defaultValue)

Converts the character to the Integer it represents, throwing an exception if the character is not numeric.

This method coverts the char '1' to the int 1 and so on.

   CharUtils.toIntValue('3', -1)  = 3
   CharUtils.toIntValue('A', -1)  = -1

Parameters:
ch - the character to convert
defaultValue - the default value to use if the character is not numeric
Returns:
the int value of the character

toIntValue

public static int toIntValue(java.lang.Character ch)

Converts the character to the Integer it represents, throwing an exception if the character is not numeric.

This method coverts the char '1' to the int 1 and so on.

   CharUtils.toIntValue(null) = IllegalArgumentException
   CharUtils.toIntValue('3')  = 3
   CharUtils.toIntValue('A')  = IllegalArgumentException

Parameters:
ch - the character to convert, not null
Returns:
the int value of the character
Throws:
java.lang.IllegalArgumentException - if the Character is not ASCII numeric or is null

toIntValue

public static int toIntValue(java.lang.Character ch,
                             int defaultValue)

Converts the character to the Integer it represents, throwing an exception if the character is not numeric.

This method coverts the char '1' to the int 1 and so on.

   CharUtils.toIntValue(null, -1) = -1
   CharUtils.toIntValue('3', -1)  = 3
   CharUtils.toIntValue('A', -1)  = -1

Parameters:
ch - the character to convert
defaultValue - the default value to use if the character is not numeric
Returns:
the int value of the character

toString

public static java.lang.String toString(char ch)

Converts the character to a String that contains the one character.

For ASCII 7 bit characters, this uses a cache that will return the same String object each time.

   CharUtils.toString(' ')  = " "
   CharUtils.toString('A')  = "A"

Parameters:
ch - the character to convert
Returns:
a String containing the one specified character

toString

public static java.lang.String toString(java.lang.Character ch)

Converts the character to a String that contains the one character.

For ASCII 7 bit characters, this uses a cache that will return the same String object each time.

If null is passed in, null will be returned.

   CharUtils.toString(null) = null
   CharUtils.toString(' ')  = " "
   CharUtils.toString('A')  = "A"

Parameters:
ch - the character to convert
Returns:
a String containing the one specified character

unicodeEscaped

public static java.lang.String unicodeEscaped(char ch)

Converts the string to the unicode format ' '.

This format is the Java source code format.

   CharUtils.unicodeEscaped(' ') = " "
   CharUtils.unicodeEscaped('A') = "A"

Parameters:
ch - the character to convert
Returns:
the escaped unicode string

unicodeEscaped

public static java.lang.String unicodeEscaped(java.lang.Character ch)

Converts the string to the unicode format ' '.

This format is the Java source code format.

If null is passed in, null will be returned.

   CharUtils.unicodeEscaped(null) = null
   CharUtils.unicodeEscaped(' ')  = " "
   CharUtils.unicodeEscaped('A')  = "A"

Parameters:
ch - the character to convert, may be null
Returns:
the escaped unicode string, null if null input

isAscii

public static boolean isAscii(char ch)

Checks whether the character is ASCII 7 bit.

   CharUtils.isAscii('a')  = true
   CharUtils.isAscii('A')  = true
   CharUtils.isAscii('3')  = true
   CharUtils.isAscii('-')  = true
   CharUtils.isAscii('\n') = true
   CharUtils.isAscii('©') = false

Parameters:
ch - the character to check
Returns:
true if less than 128

isAsciiPrintable

public static boolean isAsciiPrintable(char ch)

Checks whether the character is ASCII 7 bit printable.

   CharUtils.isAsciiPrintable('a')  = true
   CharUtils.isAsciiPrintable('A')  = true
   CharUtils.isAsciiPrintable('3')  = true
   CharUtils.isAsciiPrintable('-')  = true
   CharUtils.isAsciiPrintable('\n') = false
   CharUtils.isAsciiPrintable('©') = false

Parameters:
ch - the character to check
Returns:
true if between 32 and 126 inclusive

isAsciiControl

public static boolean isAsciiControl(char ch)

Checks whether the character is ASCII 7 bit control.

   CharUtils.isAsciiControl('a')  = false
   CharUtils.isAsciiControl('A')  = false
   CharUtils.isAsciiControl('3')  = false
   CharUtils.isAsciiControl('-')  = false
   CharUtils.isAsciiControl('\n') = true
   CharUtils.isAsciiControl('©') = false

Parameters:
ch - the character to check
Returns:
true if less than 32 or equals 127

isAsciiAlpha

public static boolean isAsciiAlpha(char ch)

Checks whether the character is ASCII 7 bit alphabetic.

   CharUtils.isAsciiAlpha('a')  = true
   CharUtils.isAsciiAlpha('A')  = true
   CharUtils.isAsciiAlpha('3')  = false
   CharUtils.isAsciiAlpha('-')  = false
   CharUtils.isAsciiAlpha('\n') = false
   CharUtils.isAsciiAlpha('©') = false

Parameters:
ch - the character to check
Returns:
true if between 65 and 90 or 97 and 122 inclusive

isAsciiAlphaUpper

public static boolean isAsciiAlphaUpper(char ch)

Checks whether the character is ASCII 7 bit alphabetic upper case.

   CharUtils.isAsciiAlphaUpper('a')  = false
   CharUtils.isAsciiAlphaUpper('A')  = true
   CharUtils.isAsciiAlphaUpper('3')  = false
   CharUtils.isAsciiAlphaUpper('-')  = false
   CharUtils.isAsciiAlphaUpper('\n') = false
   CharUtils.isAsciiAlphaUpper('©') = false

Parameters:
ch - the character to check
Returns:
true if between 65 and 90 inclusive

isAsciiAlphaLower

public static boolean isAsciiAlphaLower(char ch)

Checks whether the character is ASCII 7 bit alphabetic lower case.

   CharUtils.isAsciiAlphaLower('a')  = true
   CharUtils.isAsciiAlphaLower('A')  = false
   CharUtils.isAsciiAlphaLower('3')  = false
   CharUtils.isAsciiAlphaLower('-')  = false
   CharUtils.isAsciiAlphaLower('\n') = false
   CharUtils.isAsciiAlphaLower('©') = false

Parameters:
ch - the character to check
Returns:
true if between 97 and 122 inclusive

isAsciiNumeric

public static boolean isAsciiNumeric(char ch)

Checks whether the character is ASCII 7 bit numeric.

   CharUtils.isAsciiNumeric('a')  = false
   CharUtils.isAsciiNumeric('A')  = false
   CharUtils.isAsciiNumeric('3')  = true
   CharUtils.isAsciiNumeric('-')  = false
   CharUtils.isAsciiNumeric('\n') = false
   CharUtils.isAsciiNumeric('©') = false

Parameters:
ch - the character to check
Returns:
true if between 48 and 57 inclusive

isAsciiAlphanumeric

public static boolean isAsciiAlphanumeric(char ch)

Checks whether the character is ASCII 7 bit numeric.

   CharUtils.isAsciiAlphanumeric('a')  = true
   CharUtils.isAsciiAlphanumeric('A')  = true
   CharUtils.isAsciiAlphanumeric('3')  = true
   CharUtils.isAsciiAlphanumeric('-')  = false
   CharUtils.isAsciiAlphanumeric('\n') = false
   CharUtils.isAsciiAlphanumeric('©') = false

Parameters:
ch - the character to check
Returns:
true if between 48 and 57 or 65 and 90 or 97 and 122 inclusive
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