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>last modified date/time</b> of two files for order 027 * (see {@link FileUtils#lastModifiedUnchecked(File)}). 028 * <p> 029 * This comparator can be used to sort lists or arrays of files 030 * by their last modified date/time. 031 * <p> 032 * Example of sorting a list of files using the 033 * {@link #LASTMODIFIED_COMPARATOR} singleton instance: 034 * <pre> 035 * List<File> list = ... 036 * ((AbstractFileComparator) LastModifiedFileComparator.LASTMODIFIED_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 #LASTMODIFIED_REVERSE} singleton instance: 041 * <pre> 042 * File[] array = ... 043 * ((AbstractFileComparator) LastModifiedFileComparator.LASTMODIFIED_REVERSE).sort(array); 044 * </pre> 045 * <p> 046 * 047 * @since 1.4 048 */ 049public class LastModifiedFileComparator extends AbstractFileComparator implements Serializable { 050 051 private static final long serialVersionUID = 7372168004395734046L; 052 053 /** Last modified comparator instance. */ 054 public static final Comparator<File> LASTMODIFIED_COMPARATOR = new LastModifiedFileComparator(); 055 056 /** Reverse last modified comparator instance. */ 057 public static final Comparator<File> LASTMODIFIED_REVERSE = new ReverseFileComparator(LASTMODIFIED_COMPARATOR); 058 059 /** 060 * Compares the last the last modified date/time of two files. 061 * 062 * @param file1 The first file to compare. 063 * @param file2 The second file to compare. 064 * @return a negative value if the first file's last modified date/time is less than the second, zero if the last 065 * modified date/time are the same and a positive value if the first files last modified date/time is 066 * greater than the second file. 067 */ 068 @Override 069 public int compare(final File file1, final File file2) { 070 final long result = FileUtils.lastModifiedUnchecked(file1) - FileUtils.lastModifiedUnchecked(file2); 071 if (result < 0) { 072 return -1; 073 } 074 if (result > 0) { 075 return 1; 076 } 077 return 0; 078 } 079}