001/**
002 * Copyright 2005-2015 The Kuali Foundation
003 *
004 * Licensed under the Educational Community License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.opensource.org/licenses/ecl2.php
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.kuali.rice.krad.comparator;
017
018import org.kuali.rice.core.web.format.DateFormatter;
019
020import java.io.Serializable;
021import java.util.Comparator;
022import java.util.Date;
023
024public class TemporalValueComparator implements Comparator, Serializable {
025    private static final TemporalValueComparator theInstance = new TemporalValueComparator();
026    
027    public TemporalValueComparator() {
028    }
029    
030    public static TemporalValueComparator getInstance() {
031        return theInstance;
032    }
033    
034    public int compare(Object o1, Object o2) {
035
036        // null guard. non-null value is greater. equal if both are null
037        if (null == o1 || null == o2) {
038            return null == o1 && null == o2 ? 0 : null == o1 ? -1 : 1;
039        }
040
041        String s1 = (String) o1;
042        String s2 = (String) o2;
043
044        DateFormatter f1 = new DateFormatter();
045
046        Date d1 = (Date) f1.convertFromPresentationFormat(s1);
047        Date d2 = (Date) f1.convertFromPresentationFormat(s2);
048        
049        if (null == d1 || null == d2) {
050            return null == d1 && null == d2 ? 0 : null == d1 ? -1 : 1;
051        }
052
053        return d1.equals(d2) ? 0 : d1.before(d2) ? -1 : 1;
054    }
055}