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Commons IO example source code file (DirectoryFileComparator.java)

This example Commons IO source code file (DirectoryFileComparator.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

abstractfilecomparator, abstractfilecomparator, comparator, comparator, directory_comparator, directory_reverse, directory_reverse, directoryfilecomparator, directoryfilecomparator, file, io, reversecomparator, serializable, util

The Commons IO DirectoryFileComparator.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,
 * 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;

 * Compare two files using the {@link File#isDirectory()} method.
 * <p>
 * This comparator can be used to sort lists or arrays by directories and files.
 * <p>
 * Example of sorting a list of files/directories using the
 * {@link #DIRECTORY_COMPARATOR} singleton instance:
 * <pre>
 *       List<File> list = ...
 *       DirectoryFileComparator.DIRECTORY_COMPARATOR.sort(list);
 * </pre>
 * <p>
 * Example of doing a <i>reverse sort of an array of files/directories using the
 * {@link #DIRECTORY_REVERSE} singleton instance:
 * <pre>
 *       File[] array = ...
 *       DirectoryFileComparator.DIRECTORY_REVERSE.sort(array);
 * </pre>
 * <p>
 * @version $Revision$ $Date$
 * @since Commons IO 2.0
public class DirectoryFileComparator extends AbstractFileComparator implements Serializable {

    /** Singleton default comparator instance */
    public static final Comparator<File> DIRECTORY_COMPARATOR = new DirectoryFileComparator();

    /** Singleton reverse default comparator instance */
    public static final Comparator<File> DIRECTORY_REVERSE = new ReverseComparator(DIRECTORY_COMPARATOR);

     * Compare the two files using the {@link File#isDirectory()} method.
     * @param file1 The first file to compare
     * @param file2 The second file to compare
     * @return the result of calling file1's
     * {@link File#compareTo(File)} with file2 as the parameter.
    public int compare(File file1, File file2) {
        return (getType(file1) - getType(file2));

     * Convert type to numeric value.
     * @param file The file
     * @return 1 for directories and 2 for files
    private int getType(File file) {
        if (file.isDirectory()) {
            return 1;
        } else {
            return 2;

Other Commons IO examples (source code examples)

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

my book on functional programming


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