/*
* 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 $Revision: 1003216 $ $Date: 2010-09-30 15:39:21 -0400 (Thu, 30 Sep 2010) $
* @since Commons IO 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 + "]";
}
}
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