    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.text.Collator;
    025import java.util.Comparator;
    026
    027/**
    028 * A comparator that sorts Strings using a Collator. This class is needed
    029 * because, even though Collator implements
    030 * <code>Comparator&lt;Object&gt;</code> and the required
    031 * <code>compare(String, String)</code> method, you can't safely cast Collator
    032 * to <code>Comparator&lt;String&gt;</code>.
    033 *
    034 */
    035public class CollatorComparator implements Comparator<String>
    036{
    037    // A special singleton instance for quick access
    038    public static final Comparator<String> DEFAULT_LOCALE_COMPARATOR = new CollatorComparator();
    039
    040    protected Collator m_collator;
    041
    042    /**
    043     * Default constructor uses the current locale's collator.
    044     */
    045    public CollatorComparator()
    046    {
    047        m_collator = Collator.getInstance();
    048    }
    049
    050    /**
    051     * Construct with a specific collator.
    052     *
    053     * @param collator the collator to be used for comparisons
    054     */
    055    public CollatorComparator(final Collator collator )
    056    {
    057        m_collator = collator;
    058    }
    059
    060    /*
    061     * (non-Javadoc)
    062     * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
    063     */
    064    @Override
    065    public int compare(final String str1, final String str2 )
    066    {
    067        if( StringUtils.equals( str1, str2 ) ) {
    068            return 0; // the same object
    069        }
    070        if( str1 == null ) {
    071            return -1; // str1 is null and str2 isn't so str1 is smaller
    072        }
    073        if( str2 == null ) {
    074            return 1; // str2 is null and str1 isn't so str1 is bigger
    075        }
    076        return m_collator.compare( str1, str2 );
    077    }
    078
    079    /**
    080     * Specify a new collator.
    081     *
    082     * @param collator the collator to be used from now on
    083     */
    084    public void setCollator(final Collator collator )
    085    {
    086        m_collator = collator;
    087    }
    088}