ExtensionFileComparator (Apache Commons IO 2.5 API)

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

Version:

$Id: ExtensionFileComparator.java 1642757 2014-12-01 21:09:30Z sebb $

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

Methods
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
equals

- 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

Class ExtensionFileComparator

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Comparator

Field Detail

EXTENSION_COMPARATOR

EXTENSION_REVERSE

EXTENSION_INSENSITIVE_COMPARATOR

EXTENSION_INSENSITIVE_REVERSE

EXTENSION_SYSTEM_COMPARATOR

EXTENSION_SYSTEM_REVERSE

Constructor Detail

ExtensionFileComparator

ExtensionFileComparator

Method Detail

compare

toString

sort

sort