Package org.apache.commons.io.comparator

Class 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 Detail

      • 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