001    /**
002     * Copyright 2005-2012 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     */
016    package org.kuali.rice.krad.comparator;
017    
018    import java.io.Serializable;
019    import java.util.Comparator;
020    
021    public 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    }