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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.comparator;
18  
19  import java.io.File;
20  import java.io.Serializable;
21  import java.util.Comparator;
22  
23  import org.apache.commons.io.IOCase;
24  
25  /**
26   * Compare the <b>path</b> of two files for order (see {@link File#getPath()}).
27   * <p>
28   * This comparator can be used to sort lists or arrays of files
29   * by their path either in a case-sensitive, case-insensitive or
30   * system dependent case sensitive way. A number of singleton instances
31   * are provided for the various case sensitivity options (using {@link IOCase})
32   * and the reverse of those options.
33   * <p>
34   * Example of a <i>case-sensitive</i> file path sort using the
35   * {@link #PATH_COMPARATOR} singleton instance:
36   * <pre>
37   *       List&lt;File&gt; list = ...
38   *       ((AbstractFileComparator) PathFileComparator.PATH_COMPARATOR).sort(list);
39   * </pre>
40   * <p>
41   * Example of a <i>reverse case-insensitive</i> file path sort using the
42   * {@link #PATH_INSENSITIVE_REVERSE} singleton instance:
43   * <pre>
44   *       File[] array = ...
45   *       ((AbstractFileComparator) PathFileComparator.PATH_INSENSITIVE_REVERSE).sort(array);
46   * </pre>
47   * <p>
48   *
49   * @since 1.4
50   */
51  public class PathFileComparator extends AbstractFileComparator implements Serializable {
52  
53      private static final long serialVersionUID = 6527501707585768673L;
54  
55      /** Case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
56      public static final Comparator<File> PATH_COMPARATOR = new PathFileComparator();
57  
58      /** Reverse case-sensitive path comparator instance (see {@link IOCase#SENSITIVE}) */
59      public static final Comparator<File> PATH_REVERSE = new ReverseComparator(PATH_COMPARATOR);
60  
61      /** Case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
62      public static final Comparator<File> PATH_INSENSITIVE_COMPARATOR = new PathFileComparator(IOCase.INSENSITIVE);
63  
64      /** Reverse case-insensitive path comparator instance (see {@link IOCase#INSENSITIVE}) */
65      public static final Comparator<File> PATH_INSENSITIVE_REVERSE = new ReverseComparator(PATH_INSENSITIVE_COMPARATOR);
66  
67      /** System sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
68      public static final Comparator<File> PATH_SYSTEM_COMPARATOR = new PathFileComparator(IOCase.SYSTEM);
69  
70      /** Reverse system sensitive path comparator instance (see {@link IOCase#SYSTEM}) */
71      public static final Comparator<File> PATH_SYSTEM_REVERSE = new ReverseComparator(PATH_SYSTEM_COMPARATOR);
72  
73      /** Whether the comparison is case sensitive. */
74      private final IOCase caseSensitivity;
75  
76      /**
77       * Construct a case sensitive file path comparator instance.
78       */
79      public PathFileComparator() {
80          this.caseSensitivity = IOCase.SENSITIVE;
81      }
82  
83      /**
84       * Construct a file path comparator instance with the specified case-sensitivity.
85       *
86       * @param caseSensitivity  how to handle case sensitivity, null means case-sensitive
87       */
88      public PathFileComparator(final IOCase caseSensitivity) {
89          this.caseSensitivity = caseSensitivity == null ? IOCase.SENSITIVE : caseSensitivity;
90      }
91  
92      /**
93       * Compare the paths of two files the specified case sensitivity.
94       * 
95       * @param file1 The first file to compare
96       * @param file2 The second file to compare
97       * @return a negative value if the first file's path
98       * is less than the second, zero if the paths are the
99       * same and a positive value if the first files path
100      * is greater than the second file.
101      * 
102      */
103     @Override
104     public int compare(final File file1, final File file2) {
105         return caseSensitivity.checkCompareTo(file1.getPath(), file2.getPath());
106     }
107 
108     /**
109      * String representation of this file comparator.
110      *
111      * @return String representation of this file comparator
112      */
113     @Override
114     public String toString() {
115         return super.toString() + "[caseSensitivity=" + caseSensitivity + "]";
116     }
117 }