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 import org.apache.commons.io.FileUtils; 24 25 /** 26 * Compare the <b>last modified date/time</b> of two files for order 27 * (see {@link FileUtils#lastModifiedUnchecked(File)}). 28 * <p> 29 * This comparator can be used to sort lists or arrays of files 30 * by their last modified date/time. 31 * </p> 32 * <p> 33 * Example of sorting a list of files using the 34 * {@link #LASTMODIFIED_COMPARATOR} singleton instance: 35 * </p> 36 * <pre> 37 * List<File> list = ... 38 * ((AbstractFileComparator) LastModifiedFileComparator.LASTMODIFIED_COMPARATOR).sort(list); 39 * </pre> 40 * <p> 41 * Example of doing a <i>reverse</i> sort of an array of files using the 42 * {@link #LASTMODIFIED_REVERSE} singleton instance: 43 * </p> 44 * <pre> 45 * File[] array = ... 46 * ((AbstractFileComparator) LastModifiedFileComparator.LASTMODIFIED_REVERSE).sort(array); 47 * </pre> 48 * <h2>Deprecating Serialization</h2> 49 * <p> 50 * <em>Serialization is deprecated and will be removed in 3.0.</em> 51 * </p> 52 * 53 * @since 1.4 54 */ 55 public class LastModifiedFileComparator extends AbstractFileComparator implements Serializable { 56 57 private static final long serialVersionUID = 7372168004395734046L; 58 59 /** Last modified comparator instance. */ 60 public static final Comparator<File> LASTMODIFIED_COMPARATOR = new LastModifiedFileComparator(); 61 62 /** Reverse last modified comparator instance. */ 63 public static final Comparator<File> LASTMODIFIED_REVERSE = new ReverseFileComparator(LASTMODIFIED_COMPARATOR); 64 65 /** 66 * Compares the last modified date/time of two files. 67 * 68 * @param file1 The first file to compare. 69 * @param file2 The second file to compare. 70 * @return a negative value if the first file's last modified date/time is less than the second, zero if the last 71 * modified date/time are the same and a positive value if the first files last modified date/time is 72 * greater than the second file. 73 */ 74 @Override 75 public int compare(final File file1, final File file2) { 76 final long result = FileUtils.lastModifiedUnchecked(file1) - FileUtils.lastModifiedUnchecked(file2); 77 if (result < 0) { 78 return -1; 79 } 80 if (result > 0) { 81 return 1; 82 } 83 return 0; 84 } 85 }