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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 can be written to.
23   * <p>
24   * Example, showing how to print out a list of the
25   * current directory's <i>writable</i> files:
26   *
27   * <pre>
28   * File dir = new File(".");
29   * String[] files = dir.list( CanWriteFileFilter.CAN_WRITE );
30   * for ( int i = 0; i &lt; files.length; i++ ) {
31   *     System.out.println(files[i]);
32   * }
33   * </pre>
34   *
35   * <p>
36   * Example, showing how to print out a list of the
37   * current directory's <i>un-writable</i> files:
38   *
39   * <pre>
40   * File dir = new File(".");
41   * String[] files = dir.list( CanWriteFileFilter.CANNOT_WRITE );
42   * for ( int i = 0; i &lt; files.length; i++ ) {
43   *     System.out.println(files[i]);
44   * }
45   * </pre>
46   *
47   * <p>
48   * <b>N.B.</b> For read-only files, use 
49   *    <code>CanReadFileFilter.READ_ONLY</code>.
50   *
51   * @since Commons IO 1.3
52   * @version $Revision: 437567 $
53   */
54  public class CanWriteFileFilter extends AbstractFileFilter {
55      
56      /** Singleton instance of <i>writable</i> filter */
57      public static final IOFileFilter CAN_WRITE = new CanWriteFileFilter();
58  
59      /** Singleton instance of not <i>writable</i> filter */
60      public static final IOFileFilter CANNOT_WRITE = new NotFileFilter(CAN_WRITE);
61  
62      /**
63       * Restrictive consructor.
64       */
65      protected CanWriteFileFilter() {
66      }
67      
68      /**
69       * Checks to see if the file can be written to.
70       * 
71       * @param file  the File to check
72       * @return <code>true</code> if the file can be
73       *  written to, otherwise <code>false</code>.
74       */
75      public boolean accept(File file) {
76          return file.canWrite();
77      }
78      
79  }