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 hidden.
24 * <p>
25 * Example, showing how to print out a list of the
26 * current directory's <i>hidden</i> files:
27 *
28 * <pre>
29 * File dir = new File(".");
30 * String[] files = dir.list( HiddenFileFilter.HIDDEN );
31 * for ( int i = 0; i &lt; files.length; i++ ) {
32 *     System.out.println(files[i]);
33 * }
34 * </pre>
35 *
36 * <p>
37 * Example, showing how to print out a list of the
38 * current directory's <i>visible</i> (i.e. not hidden) files:
39 *
40 * <pre>
41 * File dir = new File(".");
42 * String[] files = dir.list( HiddenFileFilter.VISIBLE );
43 * for ( int i = 0; i &lt; files.length; i++ ) {
44 *     System.out.println(files[i]);
45 * }
46 * </pre>
47 *
48 * @since Commons IO 1.3
49 * @version $Revision: 587916 $
50 */
51public class HiddenFileFilter extends AbstractFileFilter implements Serializable {
52
53    /** Singleton instance of <i>hidden</i> filter */
54    public static final IOFileFilter HIDDEN  = new HiddenFileFilter();
55
56    /** Singleton instance of <i>visible</i> filter */
57    public static final IOFileFilter VISIBLE = new NotFileFilter(HIDDEN);
58
59    /**
60     * Restrictive consructor.
61     */
62    protected HiddenFileFilter() {
63    }
64
65    /**
66     * Checks to see if the file is hidden.
67     *
68     * @param file  the File to check
69     * @return <code>true</code> if the file is
70     *  <i>hidden</i>, otherwise <code>false</code>.
71     */
72    public boolean accept(File file) {
73        return file.isHidden();
74    }
75
76}
77