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 /**
24 * Compare two files using the {@link File#isDirectory()} method.
25 * <p>
26 * This comparator can be used to sort lists or arrays by directories and files.
27 * <p>
28 * Example of sorting a list of files/directories using the
29 * {@link #DIRECTORY_COMPARATOR} singleton instance:
30 * <pre>
31 * List<File> list = ...
32 * ((AbstractFileComparator) DirectoryFileComparator.DIRECTORY_COMPARATOR).sort(list);
33 * </pre>
34 * <p>
35 * Example of doing a <i>reverse</i> sort of an array of files/directories using the
36 * {@link #DIRECTORY_REVERSE} singleton instance:
37 * <pre>
38 * File[] array = ...
39 * ((AbstractFileComparator) DirectoryFileComparator.DIRECTORY_REVERSE).sort(array);
40 * </pre>
41 * <p>
42 *
43 * @version $Id: DirectoryFileComparator.java 1469107 2013-04-17 23:45:53Z sebb $
44 * @since 2.0
45 */
46 public class DirectoryFileComparator extends AbstractFileComparator implements Serializable {
47
48 /** Singleton default comparator instance */
49 public static final Comparator<File> DIRECTORY_COMPARATOR = new DirectoryFileComparator();
50
51 /** Singleton reverse default comparator instance */
52 public static final Comparator<File> DIRECTORY_REVERSE = new ReverseComparator(DIRECTORY_COMPARATOR);
53
54 /**
55 * Compare the two files using the {@link File#isDirectory()} method.
56 *
57 * @param file1 The first file to compare
58 * @param file2 The second file to compare
59 * @return the result of calling file1's
60 * {@link File#compareTo(File)} with file2 as the parameter.
61 */
62 public int compare(final File file1, final File file2) {
63 return getType(file1) - getType(file2);
64 }
65
66 /**
67 * Convert type to numeric value.
68 *
69 * @param file The file
70 * @return 1 for directories and 2 for files
71 */
72 private int getType(final File file) {
73 if (file.isDirectory()) {
74 return 1;
75 } else {
76 return 2;
77 }
78 }
79 }