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.filefilter;
18
19import java.io.File;
20import java.io.Serializable;
21
22/**
23 * This filter accepts <code>File</code>s that are directories.
24 * <p>
25 * For example, here is how to print out a list of the
26 * current directory's subdirectories:
27 *
28 * <pre>
29 * File dir = new File(".");
30 * String[] files = dir.list( DirectoryFileFilter.INSTANCE );
31 * for ( int i = 0; i &lt; files.length; i++ ) {
32 *     System.out.println(files[i]);
33 * }
34 * </pre>
35 *
36 * @since Commons IO 1.0
37 * @version $Revision: 587916 $ $Date: 2007-10-24 16:53:07 +0100 (Wed, 24 Oct 2007) $
38 *
39 * @author Stephen Colebourne
40 * @author Peter Donald
41 */
42public class DirectoryFileFilter extends AbstractFileFilter implements Serializable {
43
44    /**
45     * Singleton instance of directory filter.
46     * @since Commons IO 1.3
47     */
48    public static final IOFileFilter DIRECTORY = new DirectoryFileFilter();
49    /**
50     * Singleton instance of directory filter.
51     * Please use the identical DirectoryFileFilter.DIRECTORY constant.
52     * The new name is more JDK 1.5 friendly as it doesn't clash with other
53     * values when using static imports.
54     */
55    public static final IOFileFilter INSTANCE = DIRECTORY;
56
57    /**
58     * Restrictive consructor.
59     */
60    protected DirectoryFileFilter() {
61    }
62
63    /**
64     * Checks to see if the file is a directory.
65     *
66     * @param file  the File to check
67     * @return true if the file is a directory
68     */
69    public boolean accept(File file) {
70        return file.isDirectory();
71    }
72
73}
74