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; 022 023/** 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 * ((AbstractFileComparator) 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 * ((AbstractFileComparator) DirectoryFileComparator.DIRECTORY_REVERSE).sort(array); 040 * </pre> 041 * <p> 042 * 043 * @version $Id: DirectoryFileComparator.java 1642757 2014-12-01 21:09:30Z sebb $ 044 * @since 2.0 045 */ 046public class DirectoryFileComparator extends AbstractFileComparator implements Serializable { 047 048 private static final long serialVersionUID = 296132640160964395L; 049 050 /** Singleton default comparator instance */ 051 public static final Comparator<File> DIRECTORY_COMPARATOR = new DirectoryFileComparator(); 052 053 /** Singleton reverse default comparator instance */ 054 public static final Comparator<File> DIRECTORY_REVERSE = new ReverseComparator(DIRECTORY_COMPARATOR); 055 056 /** 057 * Compare the two files using the {@link File#isDirectory()} method. 058 * 059 * @param file1 The first file to compare 060 * @param file2 The second file to compare 061 * @return the result of calling file1's 062 * {@link File#compareTo(File)} with file2 as the parameter. 063 */ 064 public int compare(final File file1, final File file2) { 065 return getType(file1) - getType(file2); 066 } 067 068 /** 069 * Convert type to numeric value. 070 * 071 * @param file The file 072 * @return 1 for directories and 2 for files 073 */ 074 private int getType(final File file) { 075 if (file.isDirectory()) { 076 return 1; 077 } else { 078 return 2; 079 } 080 } 081}