1/*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements.  See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License.  You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17package org.apache.commons.io.comparator;
18
19import java.io.File;
20import java.io.Serializable;
21import java.util.Comparator;
22
23import org.apache.commons.io.IOCase;
24
25/**
26 * Compare the <b>path</b> of two files for order (see {@link File#getPath()}).
27 * <p>
28 * This comparator can be used to sort lists or arrays of files
29 * by their path either in a case-sensitive, case-insensitive or
30 * system dependant case sensitive way. A number of singleton instances
31 * are provided for the various case sensitivity options (using {@link IOCase})
32 * and the reverse of those options.
33 * <p>
34 * Example of a <i>case-sensitive</i> file path sort using the
35 * {@link #PATH_COMPARATOR} singleton instance:
36 * <pre>
37 *       List&lt;File&gt; list = ...
38 *       Collections.sort(list, PathFileComparator.PATH_COMPARATOR);
39 * </pre>
40 * <p>
41 * Example of a <i>reverse case-insensitive</i> file path sort using the
42 * {@link #PATH_INSENSITIVE_REVERSE} singleton instance:
43 * <pre>
44 *       File[] array = ...
45 *       Arrays.sort(array, PathFileComparator.PATH_INSENSITIVE_REVERSE);
46 * </pre>
47 * <p>
48 *
49 * @version $Revision: 609243 $ $Date: 2008-01-06 00:30:42 +0000 (Sun, 06 Jan 2008) $
50 * @since Commons IO 1.4
51 */
52public class PathFileComparator implements Comparator<File>, Serializable {
53
54    /** Case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
55    public static final Comparator<File> PATH_COMPARATOR = new PathFileComparator();
56
57    /** Reverse case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
58    public static final Comparator<File> PATH_REVERSE = new ReverseComparator<File>(PATH_COMPARATOR);
59
60    /** Case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
61    public static final Comparator<File> PATH_INSENSITIVE_COMPARATOR = new PathFileComparator(IOCase.INSENSITIVE);
62
63    /** Reverse case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
64    public static final Comparator<File> PATH_INSENSITIVE_REVERSE = new ReverseComparator<File>(PATH_INSENSITIVE_COMPARATOR);
65
66    /** System sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
67    public static final Comparator<File> PATH_SYSTEM_COMPARATOR = new PathFileComparator(IOCase.SYSTEM);
68
69    /** Reverse system sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
70    public static final Comparator<File> PATH_SYSTEM_REVERSE = new ReverseComparator<File>(PATH_SYSTEM_COMPARATOR);
71
72    /** Whether the comparison is case sensitive. */
73    private final IOCase caseSensitivity;
74
75    /**
76     * Construct a case sensitive file path comparator instance.
77     */
78    public PathFileComparator() {
79        this.caseSensitivity = IOCase.SENSITIVE;
80    }
81
82    /**
83     * Construct a file path comparator instance with the specified case-sensitivity.
84     *
85     * @param caseSensitivity  how to handle case sensitivity, null means case-sensitive
86     */
87    public PathFileComparator(IOCase caseSensitivity) {
88        this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity;
89    }
90
91    /**
92     * Compare the paths of two files the specified case sensitivity.
93     *
94     * @param obj1 The first file to compare
95     * @param obj2 The second file to compare
96     * @return a negative value if the first file's path
97     * is less than the second, zero if the paths are the
98     * same and a positive value if the first files path
99     * is greater than the second file.
100     *
101     */
102    public int compare(File file1, File file2) {
103        return caseSensitivity.checkCompareTo(file1.getPath(), file2.getPath());
104    }
105}
106