001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.codec;
019    
020    import java.util.Comparator;
021    
022    /**
023     * Compares Strings using a {@link StringEncoder}. This comparator is used to sort Strings by an encoding scheme such as
024     * Soundex, Metaphone, etc. This class can come in handy if one need to sort Strings by an encoded form of a name such
025     * as Soundex.
026     *
027     * <p>This class is immutable and thread-safe.</p>
028     *
029     * @version $Id: StringEncoderComparator.html 889935 2013-12-11 05:05:13Z ggregory $
030     */
031    public class StringEncoderComparator implements Comparator {
032    
033        /**
034         * Internal encoder instance.
035         */
036        private final StringEncoder stringEncoder;
037    
038        /**
039         * Constructs a new instance.
040         *
041         * @deprecated Creating an instance without a {@link StringEncoder} leads to a {@link NullPointerException}. Will be
042         *             removed in 2.0.
043         */
044        @Deprecated
045        public StringEncoderComparator() {
046            this.stringEncoder = null; // Trying to use this will cause things to break
047        }
048    
049        /**
050         * Constructs a new instance with the given algorithm.
051         *
052         * @param stringEncoder
053         *            the StringEncoder used for comparisons.
054         */
055        public StringEncoderComparator(StringEncoder stringEncoder) {
056            this.stringEncoder = stringEncoder;
057        }
058    
059        /**
060         * Compares two strings based not on the strings themselves, but on an encoding of the two strings using the
061         * StringEncoder this Comparator was created with.
062         *
063         * If an {@link EncoderException} is encountered, return <code>0</code>.
064         *
065         * @param o1
066         *            the object to compare
067         * @param o2
068         *            the object to compare to
069         * @return the Comparable.compareTo() return code or 0 if an encoding error was caught.
070         * @see Comparable
071         */
072        @Override
073        public int compare(Object o1, Object o2) {
074    
075            int compareCode = 0;
076    
077            try {
078                Comparable s1 = (Comparable) this.stringEncoder.encode(o1);
079                Comparable s2 = (Comparable) this.stringEncoder.encode(o2);
080                compareCode = s1.compareTo(s2);
081            } catch (EncoderException ee) {
082                compareCode = 0;
083            }
084            return compareCode;
085        }
086    
087    }