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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.filefilter;
18  
19  import java.io.File;
20  
21  /**
22   * This filter accepts <code>File</code>s that are directories.
23   * <p>
24   * For example, here is how to print out a list of the 
25   * current directory's subdirectories:
26   *
27   * <pre>
28   * File dir = new File(".");
29   * String[] files = dir.list( DirectoryFileFilter.INSTANCE );
30   * for ( int i = 0; i &lt; files.length; i++ ) {
31   *     System.out.println(files[i]);
32   * }
33   * </pre>
34   *
35   * @since Commons IO 1.0
36   * @version $Revision: 471628 $ $Date: 2006-11-06 05:06:45 +0100 (Mo, 06 Nov 2006) $
37   *
38   * @author Stephen Colebourne
39   * @author Peter Donald
40   */
41  public class DirectoryFileFilter extends AbstractFileFilter {
42  
43      /**
44       * Singleton instance of directory filter.
45       * @since Commons IO 1.3
46       */
47      public static final IOFileFilter DIRECTORY = new DirectoryFileFilter();
48      /**
49       * Singleton instance of directory filter.
50       * Please use the identical DirectoryFileFilter.DIRECTORY constant.
51       * The new name is more JDK 1.5 friendly as it doesn't clash with other
52       * values when using static imports.
53       */
54      public static final IOFileFilter INSTANCE = DIRECTORY;
55  
56      /**
57       * Restrictive consructor.
58       */
59      protected DirectoryFileFilter() {
60      }
61  
62      /**
63       * Checks to see if the file is a directory.
64       *
65       * @param file  the File to check
66       * @return true if the file is a directory
67       */
68      public boolean accept(File file) {
69          return file.isDirectory();
70      }
71  
72  }