001/* 
002    Licensed to the Apache Software Foundation (ASF) under one
003    or more contributor license agreements.  See the NOTICE file
004    distributed with this work for additional information
005    regarding copyright ownership.  The ASF licenses this file
006    to you under the Apache License, Version 2.0 (the
007    "License"); you may not use this file except in compliance
008    with the License.  You may obtain a copy of the License at
009
010       http://www.apache.org/licenses/LICENSE-2.0
011
012    Unless required by applicable law or agreed to in writing,
013    software distributed under the License is distributed on an
014    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015    KIND, either express or implied.  See the License for the
016    specific language governing permissions and limitations
017    under the License.  
018 */
019
020package org.apache.wiki.util.comparators;
021
022import org.apache.commons.lang3.StringUtils;
023
024import java.util.Comparator;
025
026/**
027 * A comparator that sorts Strings using Java's "natural" order.
028 * 
029 */
030public class JavaNaturalComparator implements Comparator<String>
031{
032    // A special singleton instance for quick access
033    public static final Comparator<String> DEFAULT_JAVA_COMPARATOR = new JavaNaturalComparator();
034
035    /*
036     * (non-Javadoc)
037     * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
038     */
039    public int compare(final String str1, final String str2 ) {
040        if (StringUtils.equals( str1, str2 ) ) {
041            return 0; // the same object
042        }
043        if( str1 == null ) {
044            return -1; // str1 is null and str2 isn't so str1 is smaller
045        }
046        if( str2 == null ) {
047            return 1; // str2 is null and str1 isn't so str1 is bigger
048        }
049        return str1.compareTo( str2 );
050    }
051}