001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.comparator;
018
019import java.io.File;
020import java.io.Serializable;
021import java.util.Comparator;
022
023/**
024 * Compares two files using the <strong>default</strong> {@link File#compareTo(File)} method.
025 * <p>
026 * This comparator can be used to sort lists or arrays of files
027 * by using the default file comparison.
028 * </p>
029 * <p>
030 * Example of sorting a list of files using the
031 * {@link #DEFAULT_COMPARATOR} singleton instance:
032 * </p>
033 * <pre>
034 *       List&lt;File&gt; list = ...
035 *       ((AbstractFileComparator) DefaultFileComparator.DEFAULT_COMPARATOR).sort(list);
036 * </pre>
037 * <p>
038 * Example of doing a <em>reverse</em> sort of an array of files using the
039 * {@link #DEFAULT_REVERSE} singleton instance:
040 * </p>
041 * <pre>
042 *       File[] array = ...
043 *       ((AbstractFileComparator) DefaultFileComparator.DEFAULT_REVERSE).sort(array);
044 * </pre>
045 * <h2>Deprecating Serialization</h2>
046 * <p>
047 * <em>Serialization is deprecated and will be removed in 3.0.</em>
048 * </p>
049 *
050 * @since 1.4
051 */
052public class DefaultFileComparator extends AbstractFileComparator implements Serializable {
053
054    private static final long serialVersionUID = 3260141861365313518L;
055
056    /** Singleton default comparator instance */
057    public static final Comparator<File> DEFAULT_COMPARATOR = new DefaultFileComparator();
058
059    /** Singleton reverse default comparator instance */
060    public static final Comparator<File> DEFAULT_REVERSE = new ReverseFileComparator(DEFAULT_COMPARATOR);
061
062    /**
063     * Constructs a new instance.
064     */
065    public DefaultFileComparator() {
066        // empty
067    }
068
069    /**
070     * Compares the two files using the {@link File#compareTo(File)} method.
071     *
072     * @param file1 The first file to compare
073     * @param file2 The second file to compare
074     * @return the result of calling file1's
075     * {@link File#compareTo(File)} with file2 as the parameter.
076     */
077    @Override
078    public int compare(final File file1, final File file2) {
079        return file1.compareTo(file2);
080    }
081}