/*

  * 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 final class StringValueComparator implements Serializable, Comparator<String> {

     private static final StringValueComparator INSTANCE = new StringValueComparator();

     private StringValueComparator() {

             //private

     }

     public static StringValueComparator getInstance() {

         return INSTANCE;

     }

     @Override

         public int compare(String o1, String o2) {

         // null guard. non-null value is greater. equal if both are null

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

             return (null == o1 && null == o2) ? 0 : ((null == o1) ? -1 : 1);

         }

         return String.CASE_INSENSITIVE_ORDER.compare(o1, o2);

     }

 }