PrefixFileFilter


1   /*
2    * Copyright 2002-2004 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.io.filefilter;
17  
18  import java.io.File  ;
19  import java.util.List  ;
20  
21  /**
22   * Filters filenames for a certain prefix.
23   * <p>
24   * For example, to print all files and directories in the 
25   * current directory whose name starts with <code>Test</code>:
26   *
27   * <pre>
28   * File dir = new File(".");
29   * String[] files = dir.list( new PrefixFileFilter("Test") );
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: 1.8 $ $Date: 2004/02/23 04:37:57 $
37   * 
38   * @author Henri Yandell
39   * @author Stephen Colebourne
40   * @author Federico Barbieri
41   * @author Serge Knystautas
42   * @author Peter Donald
43   */
44  public class PrefixFileFilter extends AbstractFileFilter {
45      
46      /** The filename prefixes to search for */
47      private String  [] prefixes;
48  
49      /**
50       * Constructs a new Prefix file filter for a single prefix.
51       * 
52       * @param prefix  the prefix to allow, must not be null
53       * @throws IllegalArgumentException if the prefix is null
54       */
55      public PrefixFileFilter(String   prefix) {
56          if (prefix == null) {
57              throw new IllegalArgumentException  ("The prefix must not be null");
58          }
59          this.prefixes = new String  [] {prefix};
60      }
61  
62      /**
63       * Constructs a new Prefix file filter for any of an array of prefixes.
64       * <p>
65       * The array is not cloned, so could be changed after constructing the
66       * instance. This would be inadvisable however.
67       * 
68       * @param prefixes  the prefixes to allow, must not be null
69       * @throws IllegalArgumentException if the prefix array is null
70       */
71      public PrefixFileFilter(String  [] prefixes) {
72          if (prefixes == null) {
73              throw new IllegalArgumentException  ("The array of prefixes must not be null");
74          }
75          this.prefixes = prefixes;
76      }
77  
78      /**
79       * Constructs a new Prefix file filter for a list of prefixes.
80       * 
81       * @param prefixes  the prefixes to allow, must not be null
82       * @throws IllegalArgumentException if the prefix list is null
83       * @throws ClassCastException if the list does not contain Strings
84       */
85      public PrefixFileFilter(List   prefixes) {
86          if (prefixes == null) {
87              throw new IllegalArgumentException  ("The list of prefixes must not be null");
88          }
89          this.prefixes = (String  []) prefixes.toArray(new String  [prefixes.size()]);
90      }
91  
92      /**
93       * Checks to see if the filename starts with the prefix.
94       * 
95       * @param file  the File to check
96       * @return true if the filename starts with one of our prefixes
97       */
98      public boolean accept(File   file) {
99          String   name = file.getName();
100         for (int i = 0; i < this.prefixes.length; i++) {
101             if (name.startsWith(this.prefixes[i])) {
102                 return true;
103             }
104         }
105         return false;
106     }
107     
108     /**
109      * Checks to see if the filename starts with the prefix.
110      * 
111      * @param file  the File directory
112      * @param name  the filename
113      * @return true if the filename starts with one of our prefixes
114      */
115     public boolean accept(File   file, String   name) {
116         for (int i = 0; i < prefixes.length; i++) {
117             if (name.startsWith(prefixes[i])) {
118                 return true;
119             }
120         }
121         return false;
122     }
123     
124 }
125
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