001/**
002 * Copyright 2005-2016 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.kns.web.comparator;
017
018import java.io.Serializable;
019import java.util.Comparator;
020
021public class NullValueComparator implements Comparator, Serializable {
022    private static final NullValueComparator theInstance = new NullValueComparator();
023    
024    public NullValueComparator() {
025    }
026
027    public static NullValueComparator getInstance() {
028        return theInstance;
029    }
030    
031    public int compare(Object o1, Object o2) {
032        if (o1 == null && o2 == null) {
033            return 0;
034        }
035        if (o1 == null) {
036            return -1;
037        }
038        else if (o2 == null) {
039            return 1;
040        }
041        else {
042            // probably won't go into this code segment, but doing it just in case
043            return CellComparatorHelper.getAppropriateValueComparatorForPropertyClass(o1.getClass()).compare(o1, o2);
044        }
045    }
046}