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 */
17 package org.apache.commons.io.comparator;
18
19 import java.io.File;
20 import java.io.Serializable;
21 import java.util.Comparator;
22
23 import org.apache.commons.io.IOCase;
24
25 /**
26 * Compare the <strong>names</strong> of two files for order (see {@link File#getName()}).
27 * <p>
28 * This comparator can be used to sort lists or arrays of files
29 * by their name either in a case-sensitive, case-insensitive or
30 * system dependent 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 * <p>
35 * Example of a <em>case-sensitive</em> file name sort using the
36 * {@link #NAME_COMPARATOR} singleton instance:
37 * </p>
38 * <pre>
39 * List<File> list = ...
40 * ((AbstractFileComparator) NameFileComparator.NAME_COMPARATOR).sort(list);
41 * </pre>
42 * <p>
43 * Example of a <em>reverse case-insensitive</em> file name sort using the
44 * {@link #NAME_INSENSITIVE_REVERSE} singleton instance:
45 * </p>
46 * <pre>
47 * File[] array = ...
48 * ((AbstractFileComparator) NameFileComparator.NAME_INSENSITIVE_REVERSE).sort(array);
49 * </pre>
50 * <h2>Deprecating Serialization</h2>
51 * <p>
52 * <em>Serialization is deprecated and will be removed in 3.0.</em>
53 * </p>
54 *
55 * @since 1.4
56 */
57 public class NameFileComparator extends AbstractFileComparator implements Serializable {
58
59 private static final long serialVersionUID = 8397947749814525798L;
60
61 /** Case-sensitive name comparator instance (see {@link IOCase#SENSITIVE}) */
62 public static final Comparator<File> NAME_COMPARATOR = new NameFileComparator();
63
64 /** Reverse case-sensitive name comparator instance (see {@link IOCase#SENSITIVE}) */
65 public static final Comparator<File> NAME_REVERSE = new ReverseFileComparator(NAME_COMPARATOR);
66
67 /** Case-insensitive name comparator instance (see {@link IOCase#INSENSITIVE}) */
68 public static final Comparator<File> NAME_INSENSITIVE_COMPARATOR = new NameFileComparator(IOCase.INSENSITIVE);
69
70 /** Reverse case-insensitive name comparator instance (see {@link IOCase#INSENSITIVE}) */
71 public static final Comparator<File> NAME_INSENSITIVE_REVERSE = new ReverseFileComparator(NAME_INSENSITIVE_COMPARATOR);
72
73 /** System sensitive name comparator instance (see {@link IOCase#SYSTEM}) */
74 public static final Comparator<File> NAME_SYSTEM_COMPARATOR = new NameFileComparator(IOCase.SYSTEM);
75
76 /** Reverse system sensitive name comparator instance (see {@link IOCase#SYSTEM}) */
77 public static final Comparator<File> NAME_SYSTEM_REVERSE = new ReverseFileComparator(NAME_SYSTEM_COMPARATOR);
78
79 /** Whether the comparison is case-sensitive. */
80 private final IOCase ioCase;
81
82 /**
83 * Constructs a case-sensitive file name comparator instance.
84 */
85 public NameFileComparator() {
86 this.ioCase = IOCase.SENSITIVE;
87 }
88
89 /**
90 * Constructs a file name comparator instance with the specified case-sensitivity.
91 *
92 * @param ioCase how to handle case sensitivity, null means case-sensitive
93 */
94 public NameFileComparator(final IOCase ioCase) {
95 this.ioCase = IOCase.value(ioCase, IOCase.SENSITIVE);
96 }
97
98 /**
99 * Compares the names of two files with the specified case sensitivity.
100 *
101 * @param file1 The first file to compare
102 * @param file2 The second file to compare
103 * @return a negative value if the first file's name
104 * is less than the second, zero if the names are the
105 * same and a positive value if the first files name
106 * is greater than the second file.
107 */
108 @Override
109 public int compare(final File file1, final File file2) {
110 return ioCase.checkCompareTo(file1.getName(), file2.getName());
111 }
112
113 /**
114 * String representation of this file comparator.
115 *
116 * @return String representation of this file comparator
117 */
118 @Override
119 public String toString() {
120 return super.toString() + "[ioCase=" + ioCase + "]";
121 }
122 }