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 */
017 package org.apache.commons.io.comparator;
018
019 import java.io.File;
020 import java.io.Serializable;
021 import java.util.Comparator;
022
023 /**
024 * Compare two files using the {@link File#isDirectory()} method.
025 * <p>
026 * This comparator can be used to sort lists or arrays by directories and files.
027 * <p>
028 * Example of sorting a list of files/directories using the
029 * {@link #DIRECTORY_COMPARATOR} singleton instance:
030 * <pre>
031 * List<File> list = ...
032 * DirectoryFileComparator.DIRECTORY_COMPARATOR.sort(list);
033 * </pre>
034 * <p>
035 * Example of doing a <i>reverse</i> sort of an array of files/directories using the
036 * {@link #DIRECTORY_REVERSE} singleton instance:
037 * <pre>
038 * File[] array = ...
039 * DirectoryFileComparator.DIRECTORY_REVERSE.sort(array);
040 * </pre>
041 * <p>
042 *
043 * @version $Revision$ $Date$
044 * @since Commons IO 2.0
045 */
046 public class DirectoryFileComparator extends AbstractFileComparator implements Serializable {
047
048 /** Singleton default comparator instance */
049 public static final Comparator<File> DIRECTORY_COMPARATOR = new DirectoryFileComparator();
050
051 /** Singleton reverse default comparator instance */
052 public static final Comparator<File> DIRECTORY_REVERSE = new ReverseComparator(DIRECTORY_COMPARATOR);
053
054 /**
055 * Compare the two files using the {@link File#isDirectory()} method.
056 *
057 * @param file1 The first file to compare
058 * @param file2 The second file to compare
059 * @return the result of calling file1's
060 * {@link File#compareTo(File)} with file2 as the parameter.
061 */
062 public int compare(File file1, File file2) {
063 return (getType(file1) - getType(file2));
064 }
065
066 /**
067 * Convert type to numeric value.
068 *
069 * @param file The file
070 * @return 1 for directories and 2 for files
071 */
072 private int getType(File file) {
073 if (file.isDirectory()) {
074 return 1;
075 } else {
076 return 2;
077 }
078 }
079 }