001    /*
002        Licensed to the Apache Software Foundation (ASF) under one
003        or more contributor license agreements.  See the NOTICE file
004        distributed with this work for additional information
005        regarding copyright ownership.  The ASF licenses this file
006        to you under the Apache License, Version 2.0 (the
007        "License"); you may not use this file except in compliance
008        with the License.  You may obtain a copy of the License at
009    
010           http://www.apache.org/licenses/LICENSE-2.0
011    
012        Unless required by applicable law or agreed to in writing,
013        software distributed under the License is distributed on an
014        "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015        KIND, either express or implied.  See the License for the
016        specific language governing permissions and limitations
017        under the License.   
018     */
019    package org.apache.wiki.util.comparators;
020    
021    import java.io.Serializable;
022    import java.util.Comparator;
023    import java.util.Date;
024    
025    import org.apache.log4j.Logger;
026    import org.apache.wiki.WikiPage;
027    
028    /**
029     *  Compares the lastModified date of its arguments.  Both o1 and o2 MUST
030     *  be WikiPage objects, or else you will receive a ClassCastException.
031     *  <p>
032     *  If the lastModified date is the same, then the next key is the page name.
033     *  If the page name is also equal, then returns 0 for equality.
034     */
035    // FIXME: Does not implement equals().
036    public class PageTimeComparator implements Comparator<WikiPage>, Serializable {
037        
038        private static final long serialVersionUID = 0L;
039    
040        private static final Logger log = Logger.getLogger( PageTimeComparator.class ); 
041    
042        /**
043         *  {@inheritDoc}
044         */
045        public int compare( WikiPage w1, WikiPage w2 ) {
046            if( w1 == null || w2 == null ) {
047                log.error( "W1 or W2 is NULL in PageTimeComparator!");
048                return 0; // FIXME: Is this correct?
049            }
050    
051            Date w1LastMod = w1.getLastModified();
052            Date w2LastMod = w2.getLastModified();
053    
054            if( w1LastMod == null ) {
055                log.error( "NULL MODIFY DATE WITH " + w1.getName() );
056                return 0;
057            } else if( w2LastMod == null ) {
058                log.error( "NULL MODIFY DATE WITH " + w2.getName() );
059                return 0;
060            }
061    
062            // This gets most recent on top
063            int timecomparison = w2LastMod.compareTo( w1LastMod );
064    
065            if( timecomparison == 0 ) {
066                return w1.compareTo( w2 );
067            }
068    
069            return timecomparison;
070        }
071    
072    }