/*

  * Copyright 2007-2008 The Kuali Foundation

  * 

  * Licensed under the Educational Community License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  * http://www.opensource.org/licenses/ecl2.php

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.kuali.rice.kns.web.comparator;

 import java.io.Serializable;

 import java.util.Comparator;

 public class NullValueComparator implements Comparator, Serializable {

     private static final NullValueComparator theInstance = new NullValueComparator();

     public NullValueComparator() {

     }

     public static NullValueComparator getInstance() {

         return theInstance;

     }

     public int compare(Object o1, Object o2) {

         if (o1 == null && o2 == null) {

             return 0;

         }

         if (o1 == null) {

             return -1;

         }

         else if (o2 == null) {

             return 1;

         }

         else {

             // probably won't go into this code segment, but doing it just in case

             return CellComparatorHelper.getAppropriateValueComparatorForPropertyClass(o1.getClass()).compare(o1, o2);

         }

     }

 }