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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 import 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  */
     42 public 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