org.apache.commons.io.comparator

Class ExtensionFileComparator

java.lang.Object

org.apache.commons.io.comparator.ExtensionFileComparator

All Implemented Interfaces:

Serializable, Comparator<File>

public class ExtensionFileComparator
extends Object
implements Serializable

Compare the file name extensions for order (see FilenameUtils.getExtension(String)).

This comparator can be used to sort lists or arrays of files by their file extension either in a case-sensitive, case-insensitive or system dependent case sensitive way. A number of singleton instances are provided for the various case sensitivity options (using IOCase) and the reverse of those options.

Example of a case-sensitive file extension sort using the EXTENSION_COMPARATOR singleton instance:

       List<File> list = ...
       ((AbstractFileComparator) ExtensionFileComparator.EXTENSION_COMPARATOR).sort(list);
 

Example of a reverse case-insensitive file extension sort using the EXTENSION_INSENSITIVE_REVERSE singleton instance:

       File[] array = ...
       ((AbstractFileComparator) ExtensionFileComparator.EXTENSION_INSENSITIVE_REVERSE).sort(array);
 

Since:

1.4

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static Comparator<File>	EXTENSION_COMPARATOR Case-sensitive extension comparator instance (see IOCase.SENSITIVE)
static Comparator<File>	EXTENSION_INSENSITIVE_COMPARATOR Case-insensitive extension comparator instance (see IOCase.INSENSITIVE)
static Comparator<File>	EXTENSION_INSENSITIVE_REVERSE Reverse case-insensitive extension comparator instance (see IOCase.INSENSITIVE)
static Comparator<File>	EXTENSION_REVERSE Reverse case-sensitive extension comparator instance (see IOCase.SENSITIVE)
static Comparator<File>	EXTENSION_SYSTEM_COMPARATOR System sensitive extension comparator instance (see IOCase.SYSTEM)
static Comparator<File>	EXTENSION_SYSTEM_REVERSE Reverse system sensitive path comparator instance (see IOCase.SYSTEM)

Constructor Summary

Constructors

Constructor and Description
ExtensionFileComparator() Construct a case sensitive file extension comparator instance.
ExtensionFileComparator(IOCase caseSensitivity) Construct a file extension comparator instance with the specified case-sensitivity.

Method Summary

Modifier and Type	Method and Description
int	compare(File file1, File file2) Compare the extensions of two files the specified case sensitivity.
File[]	sort(File... files) Sort an array of files.
List<File>	sort(List<File> files) Sort a List of files.
String	toString() String representation of this file comparator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, equals, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Field Detail

EXTENSION_COMPARATOR

public static final Comparator<File> EXTENSION_COMPARATOR

Case-sensitive extension comparator instance (see IOCase.SENSITIVE)

EXTENSION_REVERSE

public static final Comparator<File> EXTENSION_REVERSE

Reverse case-sensitive extension comparator instance (see IOCase.SENSITIVE)

EXTENSION_INSENSITIVE_COMPARATOR

public static final Comparator<File> EXTENSION_INSENSITIVE_COMPARATOR

Case-insensitive extension comparator instance (see IOCase.INSENSITIVE)

EXTENSION_INSENSITIVE_REVERSE

public static final Comparator<File> EXTENSION_INSENSITIVE_REVERSE

Reverse case-insensitive extension comparator instance (see IOCase.INSENSITIVE)

EXTENSION_SYSTEM_COMPARATOR

public static final Comparator<File> EXTENSION_SYSTEM_COMPARATOR

System sensitive extension comparator instance (see IOCase.SYSTEM)

EXTENSION_SYSTEM_REVERSE

public static final Comparator<File> EXTENSION_SYSTEM_REVERSE

Reverse system sensitive path comparator instance (see IOCase.SYSTEM)

Constructor Detail

ExtensionFileComparator

public ExtensionFileComparator()

Construct a case sensitive file extension comparator instance.

ExtensionFileComparator

public ExtensionFileComparator(IOCase caseSensitivity)

Construct a file extension comparator instance with the specified case-sensitivity.

Parameters:

caseSensitivity - how to handle case sensitivity, null means case-sensitive

Method Detail

compare

public int compare(File file1,
                   File file2)

Compare the extensions of two files the specified case sensitivity.

Specified by:

compare in interface Comparator<File>

Parameters:

file1 - The first file to compare

file2 - The second file to compare

Returns:

a negative value if the first file's extension is less than the second, zero if the extensions are the same and a positive value if the first files extension is greater than the second file.

toString

public String toString()

String representation of this file comparator.

Returns:

String representation of this file comparator

sort

public File[] sort(File... files)

Sort an array of files.

This method uses Arrays.sort(Object[], Comparator) and returns the original array.

Parameters:

files - The files to sort, may be null

Returns:

The sorted array

Since:

2.0

sort

public List<File> sort(List<File> files)

Sort a List of files.

This method uses Collections.sort(List, Comparator) and returns the original list.

Parameters:

files - The files to sort, may be null

Returns:

The sorted list

Since:

2.0