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.FileUtils;
24
25 /**
26 * Compare the <b>length/size</b> of two files for order (see
27 * {@link File#length()} and {@link FileUtils#sizeOfDirectory(File)}).
28 * <p>
29 * This comparator can be used to sort lists or arrays of files
30 * by their length/size.
31 * <p>
32 * Example of sorting a list of files using the
33 * {@link #SIZE_COMPARATOR} singleton instance:
34 * <pre>
35 * List<File> list = ...
36 * Collections.sort(list, LengthFileComparator.LENGTH_COMPARATOR);
37 * </pre>
38 * <p>
39 * Example of doing a <i>reverse</i> sort of an array of files using the
40 * {@link #SIZE_REVERSE} singleton instance:
41 * <pre>
42 * File[] array = ...
43 * Arrays.sort(array, LengthFileComparator.LENGTH_REVERSE);
44 * </pre>
45 * <p>
46 * <strong>N.B.</strong> Directories are treated as <b>zero size</b> unless
47 * <code>sumDirectoryContents</code> is <code>true</code>.
48 *
49 * @version $Revision: 619103 $ $Date: 2008-02-06 19:01:17 +0000 (Wed, 06 Feb 2008) $
50 * @since Commons IO 1.4
51 */
52 public class SizeFileComparator implements Comparator<File>, Serializable {
53
54 /** Size comparator instance - directories are treated as zero size */
55 public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();
56
57 /** Reverse size comparator instance - directories are treated as zero size */
58 public static final Comparator<File> SIZE_REVERSE = new ReverseComparator(SIZE_COMPARATOR);
59
60 /**
61 * Size comparator instance which sums the size of a directory's contents
62 * using {@link FileUtils#sizeOfDirectory(File)}
63 */
64 public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);
65
66 /**
67 * Reverse size comparator instance which sums the size of a directory's contents
68 * using {@link FileUtils#sizeOfDirectory(File)}
69 */
70 public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseComparator(SIZE_SUMDIR_COMPARATOR);
71
72 /** Whether the sum of the directory's contents should be calculated. */
73 private final boolean sumDirectoryContents;
74
75 /**
76 * Construct a file size comparator instance (directories treated as zero size).
77 */
78 public SizeFileComparator() {
79 this.sumDirectoryContents = false;
80 }
81
82 /**
83 * Construct a file size comparator instance specifying whether the size of
84 * the directory contents should be aggregated.
85 * <p>
86 * If the <code>sumDirectoryContents</code> is <code>true</code> The size of
87 * directories is calculated using {@link FileUtils#sizeOfDirectory(File)}.
88 *
89 * @param sumDirectoryContents <code>true</code> if the sum of the directoryies contents
90 * should be calculated, otherwise <code>false</code> if directories should be treated
91 * as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
92 */
93 public SizeFileComparator(boolean sumDirectoryContents) {
94 this.sumDirectoryContents = sumDirectoryContents;
95 }
96
97 /**
98 * Compare the length of two files.
99 *
100 * @param file1 The first file to compare
101 * @param file2 The second file to compare
102 * @return a negative value if the first file's length
103 * is less than the second, zero if the lengths are the
104 * same and a positive value if the first files length
105 * is greater than the second file.
106 *
107 */
108 public int compare(File file1, File file2) {
109 long size1 = 0;
110 if (file1.isDirectory()) {
111 size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
112 } else {
113 size1 = file1.length();
114 }
115 long size2 = 0;
116 if (file2.isDirectory()) {
117 size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
118 } else {
119 size2 = file2.length();
120 }
121 long result = size1 - size2;
122 if (result < 0) {
123 return -1;
124 } else if (result > 0) {
125 return 1;
126 } else {
127 return 0;
128 }
129 }
130 }