org.apache.commons.io.comparator

Class ExtensionFileComparator

Implemented Interfaces:
Comparator, Serializable

public class ExtensionFileComparator
extends java.lang.Object
implements Comparator, 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 dependant 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 = ...
       Collections.sort(list, ExtensionFileComparator.EXTENSION_COMPARATOR);
 

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

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

Version:
$Revision: 609243 $ $Date: 2008-01-06 00:30:42 +0000 (Sun, 06 Jan 2008) $
Since:
Commons IO 1.4

Field Summary

static Comparator
EXTENSION_COMPARATOR
Case-sensitive extension comparator instance (see IOCase.SENSITIVE)
static Comparator
EXTENSION_INSENSITIVE_COMPARATOR
Case-insensitive extension comparator instance (see IOCase.INSENSITIVE)
static Comparator
EXTENSION_INSENSITIVE_REVERSE
Reverse case-insensitive extension comparator instance (see IOCase.INSENSITIVE)
static Comparator
EXTENSION_REVERSE
Reverse case-sensitive extension comparator instance (see IOCase.SENSITIVE)
static Comparator
EXTENSION_SYSTEM_COMPARATOR
System sensitive extension comparator instance (see IOCase.SYSTEM)
static Comparator
EXTENSION_SYSTEM_REVERSE
Reverse system sensitive path comparator instance (see IOCase.SYSTEM)
private IOCase
caseSensitivity
Whether the comparison is case sensitive.

Constructor Summary

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

int
compare(Object obj1, Object obj2)
Compare the extensions of two files the specified case sensitivity.

Field Details

EXTENSION_COMPARATOR

public static final Comparator EXTENSION_COMPARATOR

EXTENSION_INSENSITIVE_COMPARATOR

public static final Comparator EXTENSION_INSENSITIVE_COMPARATOR

EXTENSION_INSENSITIVE_REVERSE

public static final Comparator EXTENSION_INSENSITIVE_REVERSE

EXTENSION_REVERSE

public static final Comparator EXTENSION_REVERSE

EXTENSION_SYSTEM_COMPARATOR

public static final Comparator EXTENSION_SYSTEM_COMPARATOR

EXTENSION_SYSTEM_REVERSE

public static final Comparator EXTENSION_SYSTEM_REVERSE

caseSensitivity

private final IOCase caseSensitivity
Whether the comparison is case sensitive.

Constructor Details

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 Details

compare

public int compare(Object obj1,
                   Object obj2)
Compare the extensions of two files the specified case sensitivity.
Parameters:
obj1 - The first file to compare
obj2 - 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.

Copyright (c) 2002-2009 Apache Software Foundation