001/**
002 * Copyright 2005-2014 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 java.io.Serializable;
019import java.util.Comparator;
020
021public final class StringValueComparator implements Serializable, Comparator<String> {
022    private static final StringValueComparator INSTANCE = new StringValueComparator();
023    
024    private StringValueComparator() {
025        //private
026    }
027
028    public static StringValueComparator getInstance() {
029        return INSTANCE;
030    }
031    
032    @Override
033        public int compare(String o1, String o2) {
034        // null guard. non-null value is greater. equal if both are null
035        if (null == o1 || null == o2) {
036            return (null == o1 && null == o2) ? 0 : ((null == o1) ? -1 : 1);
037        }
038
039        return String.CASE_INSENSITIVE_ORDER.compare(o1, o2);
040    }
041}