/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.io.comparator;
import java.io.File;
import java.io.Serializable;
import java.util.Comparator;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOCase;
/**
* Compare the file name <b>extensions</b> for order (see
* {@link FilenameUtils#getExtension(String)}).
* <p>
* 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 {@link IOCase}) and the reverse of
* those options.
* <p>
* Example of a <i>case-sensitive</i> file extension sort using the
* {@link #EXTENSION_COMPARATOR} singleton instance:
*
* <pre>
* List<File> list = ...
* ExtensionFileComparator.EXTENSION_COMPARATOR.sort(list);
* </pre>
* <p>
* Example of a <i>reverse case-insensitive</i> file extension sort using the
* {@link #EXTENSION_INSENSITIVE_REVERSE} singleton instance:
*
* <pre>
* File[] array = ...
* ExtensionFileComparator.EXTENSION_INSENSITIVE_REVERSE.sort(array);
* </pre>
* <p>
*
* @version $Id: ExtensionFileComparator.java 1304052 2012-03-22 20:55:29Z
* ggregory $
* @since 1.4
*/
public class ExtensionFileComparator extends AbstractFileComparator implements
Serializable {
/**
* Case-sensitive extension comparator instance (see
* {@link IOCase#SENSITIVE})
*/
public static final Comparator<File> EXTENSION_COMPARATOR = new ExtensionFileComparator();
/**
* Reverse case-sensitive extension comparator instance (see
* {@link IOCase#SENSITIVE})
*/
public static final Comparator<File> EXTENSION_REVERSE = new ReverseComparator(
EXTENSION_COMPARATOR);
/**
* Case-insensitive extension comparator instance (see
* {@link IOCase#INSENSITIVE})
*/
public static final Comparator<File> EXTENSION_INSENSITIVE_COMPARATOR = new ExtensionFileComparator(
IOCase.INSENSITIVE);
/**
* Reverse case-insensitive extension comparator instance (see
* {@link IOCase#INSENSITIVE})
*/
public static final Comparator<File> EXTENSION_INSENSITIVE_REVERSE = new ReverseComparator(
EXTENSION_INSENSITIVE_COMPARATOR);
/**
* System sensitive extension comparator instance (see {@link IOCase#SYSTEM}
* )
*/
public static final Comparator<File> EXTENSION_SYSTEM_COMPARATOR = new ExtensionFileComparator(
IOCase.SYSTEM);
/**
* Reverse system sensitive path comparator instance (see
* {@link IOCase#SYSTEM})
*/
public static final Comparator<File> EXTENSION_SYSTEM_REVERSE = new ReverseComparator(
EXTENSION_SYSTEM_COMPARATOR);
/**
* Whether the comparison is case sensitive.
*/
private final IOCase caseSensitivity;
/**
* Construct a case sensitive file extension comparator instance.
*/
public ExtensionFileComparator() {
this.caseSensitivity = IOCase.SENSITIVE;
}
/**
* Construct a file extension comparator instance with the specified
* case-sensitivity.
*
* @param caseSensitivity how to handle case sensitivity, null means
* case-sensitive
*/
public ExtensionFileComparator(IOCase caseSensitivity) {
this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE
: caseSensitivity;
}
/**
* Compare the extensions of two files the specified case sensitivity.
*
* @param file1 The first file to compare
* @param file2 The second file to compare
* @return 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.
*
*/
public int compare(File file1, File file2) {
String suffix1 = FilenameUtils.getExtension(file1.getName());
String suffix2 = FilenameUtils.getExtension(file2.getName());
return caseSensitivity.checkCompareTo(suffix1, suffix2);
}
/**
* String representation of this file comparator.
*
* @return String representation of this file comparator
*/
@Override
public String toString() {
return super.toString() + "[caseSensitivity=" + caseSensitivity + "]";
}
}