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 <b>path</b> 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 * Example of a <i>case-sensitive</i> file path sort using the
035 * {@link #PATH_COMPARATOR} singleton instance:
036 * <pre>
037 *       List&lt;File&gt; list = ...
038 *       ((AbstractFileComparator) PathFileComparator.PATH_COMPARATOR).sort(list);
039 * </pre>
040 * <p>
041 * Example of a <i>reverse case-insensitive</i> file path sort using the
042 * {@link #PATH_INSENSITIVE_REVERSE} singleton instance:
043 * <pre>
044 *       File[] array = ...
045 *       ((AbstractFileComparator) PathFileComparator.PATH_INSENSITIVE_REVERSE).sort(array);
046 * </pre>
047 * <p>
048 *
049 * @since 1.4
050 */
051public class PathFileComparator extends AbstractFileComparator implements Serializable {
052
053    private static final long serialVersionUID = 6527501707585768673L;
054
055    /** Case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
056    public static final Comparator<File> PATH_COMPARATOR = new PathFileComparator();
057
058    /** Reverse case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
059    public static final Comparator<File> PATH_REVERSE = new ReverseComparator(PATH_COMPARATOR);
060
061    /** Case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
062    public static final Comparator<File> PATH_INSENSITIVE_COMPARATOR = new PathFileComparator(IOCase.INSENSITIVE);
063
064    /** Reverse case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
065    public static final Comparator<File> PATH_INSENSITIVE_REVERSE = new ReverseComparator(PATH_INSENSITIVE_COMPARATOR);
066
067    /** System sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
068    public static final Comparator<File> PATH_SYSTEM_COMPARATOR = new PathFileComparator(IOCase.SYSTEM);
069
070    /** Reverse system sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
071    public static final Comparator<File> PATH_SYSTEM_REVERSE = new ReverseComparator(PATH_SYSTEM_COMPARATOR);
072
073    /** Whether the comparison is case sensitive. */
074    private final IOCase caseSensitivity;
075
076    /**
077     * Construct a case sensitive file path comparator instance.
078     */
079    public PathFileComparator() {
080        this.caseSensitivity = IOCase.SENSITIVE;
081    }
082
083    /**
084     * Construct a file path comparator instance with the specified case-sensitivity.
085     *
086     * @param caseSensitivity  how to handle case sensitivity, null means case-sensitive
087     */
088    public PathFileComparator(final IOCase caseSensitivity) {
089        this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity;
090    }
091
092    /**
093     * Compare the paths of two files the specified case sensitivity.
094     *
095     * @param file1 The first file to compare
096     * @param file2 The second file to compare
097     * @return a negative value if the first file's path
098     * is less than the second, zero if the paths are the
099     * same and a positive value if the first files path
100     * is greater than the second file.
101     *
102     */
103    @Override
104    public int compare(final File file1, final File file2) {
105        return caseSensitivity.checkCompareTo(file1.getPath(), file2.getPath());
106    }
107
108    /**
109     * String representation of this file comparator.
110     *
111     * @return String representation of this file comparator
112     */
113    @Override
114    public String toString() {
115        return super.toString() + "[caseSensitivity=" + caseSensitivity + "]";
116    }
117}