001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.comparator;
018
019import java.io.File;
020import java.io.Serializable;
021import java.util.Comparator;
022
023import org.apache.commons.io.FileUtils;
024
025/**
026 * Compare the <b>length/size</b> of two files for order (see
027 * {@link File#length()} and {@link FileUtils#sizeOfDirectory(File)}).
028 * <p>
029 * This comparator can be used to sort lists or arrays of files
030 * by their length/size.
031 * <p>
032 * Example of sorting a list of files using the
033 * {@link #SIZE_COMPARATOR} singleton instance:
034 * <pre>
035 *       List&lt;File&gt; list = ...
036 *       ((AbstractFileComparator) SizeFileComparator.SIZE_COMPARATOR).sort(list);
037 * </pre>
038 * <p>
039 * Example of doing a <i>reverse</i> sort of an array of files using the
040 * {@link #SIZE_REVERSE} singleton instance:
041 * <pre>
042 *       File[] array = ...
043 *       ((AbstractFileComparator) SizeFileComparator.SIZE_REVERSE).sort(array);
044 * </pre>
045 * <p>
046 * <strong>N.B.</strong> Directories are treated as <b>zero size</b> unless
047 * <code>sumDirectoryContents</code> is {@code true}.
048 *
049 * @since 1.4
050 */
051public class SizeFileComparator extends AbstractFileComparator implements Serializable {
052
053    private static final long serialVersionUID = -1201561106411416190L;
054
055    /** Size comparator instance - directories are treated as zero size */
056    public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();
057
058    /** Reverse size comparator instance - directories are treated as zero size */
059    public static final Comparator<File> SIZE_REVERSE = new ReverseComparator(SIZE_COMPARATOR);
060
061    /**
062     * Size comparator instance which sums the size of a directory's contents
063     * using {@link FileUtils#sizeOfDirectory(File)}
064     */
065    public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);
066
067    /**
068     * Reverse size comparator instance which sums the size of a directory's contents
069     * using {@link FileUtils#sizeOfDirectory(File)}
070     */
071    public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseComparator(SIZE_SUMDIR_COMPARATOR);
072
073    /** Whether the sum of the directory's contents should be calculated. */
074    private final boolean sumDirectoryContents;
075
076    /**
077     * Construct a file size comparator instance (directories treated as zero size).
078     */
079    public SizeFileComparator() {
080        this.sumDirectoryContents = false;
081    }
082
083    /**
084     * Construct a file size comparator instance specifying whether the size of
085     * the directory contents should be aggregated.
086     * <p>
087     * If the <code>sumDirectoryContents</code> is {@code true} The size of
088     * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
089     *
090     * @param sumDirectoryContents {@code true} if the sum of the directories' contents
091     *  should be calculated, otherwise {@code false} if directories should be treated
092     *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
093     */
094    public SizeFileComparator(final boolean sumDirectoryContents) {
095        this.sumDirectoryContents = sumDirectoryContents;
096    }
097
098    /**
099     * Compare the length of two files.
100     *
101     * @param file1 The first file to compare
102     * @param file2 The second file to compare
103     * @return a negative value if the first file's length
104     * is less than the second, zero if the lengths are the
105     * same and a positive value if the first files length
106     * is greater than the second file.
107     *
108     */
109    @Override
110    public int compare(final File file1, final File file2) {
111        long size1 = 0;
112        if (file1.isDirectory()) {
113            size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
114        } else {
115            size1 = file1.length();
116        }
117        long size2 = 0;
118        if (file2.isDirectory()) {
119            size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
120        } else {
121            size2 = file2.length();
122        }
123        final long result = size1 - size2;
124        if (result < 0) {
125            return -1;
126        } else if (result > 0) {
127            return 1;
128        } else {
129            return 0;
130        }
131    }
132
133    /**
134     * String representation of this file comparator.
135     *
136     * @return String representation of this file comparator
137     */
138    @Override
139    public String toString() {
140        return super.toString() + "[sumDirectoryContents=" + sumDirectoryContents + "]";
141    }
142}