1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.io.comparator; 18 19 import java.io.File; 20 import java.io.Serializable; 21 import java.util.Comparator; 22 23 /** 24 * Compare the <b>last modified date/time</b> of two files for order 25 * (see {@link File#lastModified()}). 26 * <p> 27 * This comparator can be used to sort lists or arrays of files 28 * by their last modified date/time. 29 * <p> 30 * Example of sorting a list of files using the 31 * {@link #LASTMODIFIED_COMPARATOR} singleton instance: 32 * <pre> 33 * List<File> list = ... 34 * Collections.sort(list, LastModifiedFileComparator.LASTMODIFIED_COMPARATOR); 35 * </pre> 36 * <p> 37 * Example of doing a <i>reverse</i> sort of an array of files using the 38 * {@link #LASTMODIFIED_REVERSE} singleton instance: 39 * <pre> 40 * File[] array = ... 41 * Arrays.sort(array, LastModifiedFileComparator.LASTMODIFIED_REVERSE); 42 * </pre> 43 * <p> 44 * 45 * @version $Revision: 609243 $ $Date: 2008-01-06 00:30:42 +0000 (Sun, 06 Jan 2008) $ 46 * @since Commons IO 1.4 47 */ 48 public class LastModifiedFileComparator implements Comparator<File>, Serializable { 49 50 /** Last modified comparator instance */ 51 public static final Comparator<File> LASTMODIFIED_COMPARATOR = new LastModifiedFileComparator(); 52 53 /** Reverse last modified comparator instance */ 54 public static final Comparator<File> LASTMODIFIED_REVERSE = new ReverseComparator<File>(LASTMODIFIED_COMPARATOR); 55 56 /** 57 * Compare the last the last modified date/time of two files. 58 * 59 * @param obj1 The first file to compare 60 * @param obj2 The second file to compare 61 * @return a negative value if the first file's lastmodified date/time 62 * is less than the second, zero if the lastmodified date/time are the 63 * same and a positive value if the first files lastmodified date/time 64 * is greater than the second file. 65 * 66 */ 67 public int compare(File file1, File file2) { 68 long result = file1.lastModified() - file2.lastModified(); 69 if (result < 0) { 70 return -1; 71 } else if (result > 0) { 72 return 1; 73 } else { 74 return 0; 75 } 76 } 77 } 78