1 /*
2 * Copyright 2007-2008 The Kuali Foundation
3 *
4 * Licensed under the Educational Community License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.opensource.org/licenses/ecl2.php
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package org.kuali.rice.kns.web.comparator;
17
18 import java.io.Serializable;
19 import java.util.Comparator;
20
21 public class NullValueComparator implements Comparator, Serializable {
22 private static final NullValueComparator theInstance = new NullValueComparator();
23
24 public NullValueComparator() {
25 }
26
27 public static NullValueComparator getInstance() {
28 return theInstance;
29 }
30
31 public int compare(Object o1, Object o2) {
32 if (o1 == null && o2 == null) {
33 return 0;
34 }
35 if (o1 == null) {
36 return -1;
37 }
38 else if (o2 == null) {
39 return 1;
40 }
41 else {
42 // probably won't go into this code segment, but doing it just in case
43 return CellComparatorHelper.getAppropriateValueComparatorForPropertyClass(o1.getClass()).compare(o1, o2);
44 }
45 }
46 }