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 */
17package org.apache.commons.io.comparator;
18
19import java.io.File;
20import java.io.Serializable;
21import java.util.Comparator;
22
23import 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&lt;File&gt; 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: 609243 $ $Date: 2008-01-06 00:30:42 +0000 (Sun, 06 Jan 2008) $
50 * @since Commons IO 1.4
51 */
52public 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<File>(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<File>(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 obj1 The first file to compare
101     * @param obj2 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}
131