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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   * Filters files based on size, can filter either smaller files or
23   * files equal to or larger than a given threshold.
24   * <p>
25   * For example, to print all files and directories in the
26   * current directory whose size is greater than 1 MB:
27   *
28   * <pre>
29   * File dir = new File(".");
30   * String[] files = dir.list( new SizeFileFilter(1024 * 1024) );
31   * for ( int i = 0; i &lt; files.length; i++ ) {
32   *     System.out.println(files[i]);
33   * }
34   * </pre>
35   *
36   * @author Rahul Akolkar
37   * @version $Id: SizeFileFilter.java 463570 2006-10-13 06:14:41Z niallp $
38   * @since Commons IO 1.2
39   */
40  public class SizeFileFilter extends AbstractFileFilter {
41  
42      /** The size threshold. */
43      private long size;
44      /** Whether the files accepted will be larger or smaller. */
45      private boolean acceptLarger;
46  
47      /**
48       * Constructs a new size file filter for files equal to or 
49       * larger than a certain size.
50       *
51       * @param size  the threshold size of the files
52       * @throws IllegalArgumentException if the size is negative
53       */
54      public SizeFileFilter(long size) {
55          this(size, true);
56      }
57  
58      /**
59       * Constructs a new size file filter for files based on a certain size
60       * threshold.
61       *
62       * @param size  the threshold size of the files
63       * @param acceptLarger  if true, files equal to or larger are accepted,
64       * otherwise smaller ones (but not equal to)
65       * @throws IllegalArgumentException if the size is negative
66       */
67      public SizeFileFilter(long size, boolean acceptLarger) {
68          if (size < 0) {
69              throw new IllegalArgumentException("The size must be non-negative");
70          }
71          this.size = size;
72          this.acceptLarger = acceptLarger;
73      }
74  
75      //-----------------------------------------------------------------------
76      /**
77       * Checks to see if the size of the file is favorable.
78       * <p>
79       * If size equals threshold and smaller files are required,
80       * file <b>IS NOT</b> selected.
81       * If size equals threshold and larger files are required,
82       * file <b>IS</b> selected.
83       *
84       * @param file  the File to check
85       * @return true if the filename matches
86       */
87      public boolean accept(File file) {
88          boolean smaller = file.length() < size;
89          return acceptLarger ? !smaller : smaller;
90      }
91  
92  }