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
023import org.apache.commons.io.IOCase;
024
025/**
026 * Compare the <strong>path</strong> of two files for order (see {@link File#getPath()}).
027 * <p>
028 * This comparator can be used to sort lists or arrays of files
029 * by their path either in a case-sensitive, case-insensitive or
030 * system dependent case-sensitive way. A number of singleton instances
031 * are provided for the various case sensitivity options (using {@link IOCase})
032 * and the reverse of those options.
033 * </p>
034 * <p>
035 * Example of a <em>case-sensitive</em> file path sort using the
036 * {@link #PATH_COMPARATOR} singleton instance:
037 * </p>
038 * <pre>
039 *       List&lt;File&gt; list = ...
040 *       ((AbstractFileComparator) PathFileComparator.PATH_COMPARATOR).sort(list);
041 * </pre>
042 * <p>
043 * Example of a <em>reverse case-insensitive</em> file path sort using the
044 * {@link #PATH_INSENSITIVE_REVERSE} singleton instance:
045 * </p>
046 * <pre>
047 *       File[] array = ...
048 *       ((AbstractFileComparator) PathFileComparator.PATH_INSENSITIVE_REVERSE).sort(array);
049 * </pre>
050 * <h2>Deprecating Serialization</h2>
051 * <p>
052 * <em>Serialization is deprecated and will be removed in 3.0.</em>
053 * </p>
054 * @since 1.4
055 */
056public class PathFileComparator extends AbstractFileComparator implements Serializable {
057
058    private static final long serialVersionUID = 6527501707585768673L;
059
060    /** Case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
061    public static final Comparator<File> PATH_COMPARATOR = new PathFileComparator();
062
063    /** Reverse case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
064    public static final Comparator<File> PATH_REVERSE = new ReverseFileComparator(PATH_COMPARATOR);
065
066    /** Case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
067    public static final Comparator<File> PATH_INSENSITIVE_COMPARATOR = new PathFileComparator(IOCase.INSENSITIVE);
068
069    /** Reverse case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
070    public static final Comparator<File> PATH_INSENSITIVE_REVERSE = new ReverseFileComparator(PATH_INSENSITIVE_COMPARATOR);
071
072    /** System sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
073    public static final Comparator<File> PATH_SYSTEM_COMPARATOR = new PathFileComparator(IOCase.SYSTEM);
074
075    /** Reverse system sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
076    public static final Comparator<File> PATH_SYSTEM_REVERSE = new ReverseFileComparator(PATH_SYSTEM_COMPARATOR);
077
078    /** Whether the comparison is case-sensitive. */
079    private final IOCase ioCase;
080
081    /**
082     * Constructs a case-sensitive file path comparator instance.
083     */
084    public PathFileComparator() {
085        this.ioCase = IOCase.SENSITIVE;
086    }
087
088    /**
089     * Constructs a file path comparator instance with the specified case-sensitivity.
090     *
091     * @param ioCase  how to handle case sensitivity, null means case-sensitive
092     */
093    public PathFileComparator(final IOCase ioCase) {
094        this.ioCase = IOCase.value(ioCase, IOCase.SENSITIVE);
095    }
096
097    /**
098     * Compares the paths of two files the specified case sensitivity.
099     *
100     * @param file1 The first file to compare
101     * @param file2 The second file to compare
102     * @return a negative value if the first file's path
103     * is less than the second, zero if the paths are the
104     * same and a positive value if the first files path
105     * is greater than the second file.
106     */
107    @Override
108    public int compare(final File file1, final File file2) {
109        return ioCase.checkCompareTo(file1.getPath(), file2.getPath());
110    }
111
112    /**
113     * String representation of this file comparator.
114     *
115     * @return String representation of this file comparator
116     */
117    @Override
118    public String toString() {
119        return super.toString() + "[ioCase=" + ioCase + "]";
120    }
121}