001    /**
002     * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
003     *
004     * This library is free software; you can redistribute it and/or modify it under
005     * the terms of the GNU Lesser General Public License as published by the Free
006     * Software Foundation; either version 2.1 of the License, or (at your option)
007     * any later version.
008     *
009     * This library is distributed in the hope that it will be useful, but WITHOUT
010     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
011     * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
012     * details.
013     */
014    
015    package com.liferay.portal.kernel.util;
016    
017    import java.util.Comparator;
018    
019    /**
020     * @author Shuyang Zhou
021     */
022    public class NullSafeStringComparator implements Comparator<String> {
023    
024            @Override
025            public int compare(String s1, String s2) {
026                    if (s1 == null) {
027                            if (s2 == null) {
028                                    return 0;
029                            }
030    
031                            return 1;
032                    }
033    
034                    if (s2 == null) {
035                            return -1;
036                    }
037    
038                    return s1.compareTo(s2);
039            }
040    
041    }