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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 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  */
     51 public 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