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Commons IO example source code file (SizeFileComparator.java)

This example Commons IO source code file (SizeFileComparator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Commons IO tags/keywords

comparator, comparator, file, io, override, reversecomparator, reversecomparator, serializable, serializable, size_comparator, size_reverse, size_sumdir_reverse, sizefilecomparator, sizefilecomparator, string, util

The Commons IO SizeFileComparator.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.comparator;

import java.io.File;
import java.io.Serializable;
import java.util.Comparator;

import org.apache.commons.io.FileUtils;

/**
 * Compare the <b>length/size of two files for order (see
 * {@link File#length()} and {@link FileUtils#sizeOfDirectory(File)}).
 * <p>
 * This comparator can be used to sort lists or arrays of files
 * by their length/size.
 * <p>
 * Example of sorting a list of files using the
 * {@link #SIZE_COMPARATOR} singleton instance:
 * <pre>
 *       List<File> list = ...
 *       SizeFileComparator.SIZE_COMPARATOR.sort(list);
 * </pre>
 * <p>
 * Example of doing a <i>reverse sort of an array of files using the
 * {@link #SIZE_REVERSE} singleton instance:
 * <pre>
 *       File[] array = ...
 *       SizeFileComparator.SIZE_REVERSE.sort(array);
 * </pre>
 * <p>
 * <strong>N.B. Directories are treated as zero size unless
 * <code>sumDirectoryContents is true.
 *
 * @version $Revision: 723942 $ $Date: 2008-12-06 01:24:06 +0000 (Sat, 06 Dec 2008) $
 * @since Commons IO 1.4
 */
public class SizeFileComparator extends AbstractFileComparator implements Serializable {

    /** Size comparator instance - directories are treated as zero size */
    public static final Comparator<File> SIZE_COMPARATOR = new SizeFileComparator();

    /** Reverse size comparator instance - directories are treated as zero size */
    public static final Comparator<File> SIZE_REVERSE = new ReverseComparator(SIZE_COMPARATOR);

    /**
     * Size comparator instance which sums the size of a directory's contents
     * using {@link FileUtils#sizeOfDirectory(File)}
     */
    public static final Comparator<File> SIZE_SUMDIR_COMPARATOR = new SizeFileComparator(true);

    /**
     * Reverse size comparator instance which sums the size of a directory's contents
     * using {@link FileUtils#sizeOfDirectory(File)}
     */
    public static final Comparator<File> SIZE_SUMDIR_REVERSE = new ReverseComparator(SIZE_SUMDIR_COMPARATOR);

    /** Whether the sum of the directory's contents should be calculated. */
    private final boolean sumDirectoryContents;

    /**
     * Construct a file size comparator instance (directories treated as zero size).
     */
    public SizeFileComparator() {
        this.sumDirectoryContents = false;
    }

    /**
     * Construct a file size comparator instance specifying whether the size of
     * the directory contents should be aggregated.
     * <p>
     * If the <code>sumDirectoryContents is true The size of
     * directories is calculated using  {@link FileUtils#sizeOfDirectory(File)}.
     *
     * @param sumDirectoryContents <code>true if the sum of the directoryies contents
     *  should be calculated, otherwise <code>false if directories should be treated
     *  as size zero (see {@link FileUtils#sizeOfDirectory(File)}).
     */
    public SizeFileComparator(boolean sumDirectoryContents) {
        this.sumDirectoryContents = sumDirectoryContents;
    }

    /**
     * Compare the length of two files.
     * 
     * @param file1 The first file to compare
     * @param file2 The second file to compare
     * @return a negative value if the first file's length
     * is less than the second, zero if the lengths are the
     * same and a positive value if the first files length
     * is greater than the second file.
     * 
     */
    public int compare(File file1, File file2) {
        long size1 = 0;
        if (file1.isDirectory()) {
            size1 = sumDirectoryContents && file1.exists() ? FileUtils.sizeOfDirectory(file1) : 0;
        } else {
            size1 = file1.length();
        }
        long size2 = 0;
        if (file2.isDirectory()) {
            size2 = sumDirectoryContents && file2.exists() ? FileUtils.sizeOfDirectory(file2) : 0;
        } else {
            size2 = file2.length();
        }
        long result = size1 - size2;
        if (result < 0) {
            return -1;
        } else if (result > 0) {
            return 1;
        } else {
            return 0;
        }
    }

    /**
     * String representation of this file comparator.
     *
     * @return String representation of this file comparator
     */
    @Override
    public String toString() {
        return super.toString() + "[sumDirectoryContents=" + sumDirectoryContents + "]";
    }
}

Other Commons IO examples (source code examples)

Here is a short list of links related to this Commons IO SizeFileComparator.java source code file:

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