    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
    018package org.apache.commons.codec;
    019
    020import 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 */
    030@SuppressWarnings("rawtypes")
    031// TODO ought to implement Comparator<String> but that's not possible whilst maintaining binary compatibility.
    032public class StringEncoderComparator implements Comparator {
    033
    034    /**
    035     * Internal encoder instance.
    036     */
    037    private final StringEncoder stringEncoder;
    038
    039    /**
    040     * Constructs a new instance.
    041     *
    042     * @deprecated Creating an instance without a {@link StringEncoder} leads to a {@link NullPointerException}. Will be
    043     *             removed in 2.0.
    044     */
    045    @Deprecated
    046    public StringEncoderComparator() {
    047        this.stringEncoder = null; // Trying to use this will cause things to break
    048    }
    049
    050    /**
    051     * Constructs a new instance with the given algorithm.
    052     *
    053     * @param stringEncoder
    054     *            the StringEncoder used for comparisons.
    055     */
    056    public StringEncoderComparator(final StringEncoder stringEncoder) {
    057        this.stringEncoder = stringEncoder;
    058    }
    059
    060    /**
    061     * Compares two strings based not on the strings themselves, but on an encoding of the two strings using the
    062     * StringEncoder this Comparator was created with.
    063     *
    064     * If an {@link EncoderException} is encountered, return {@code 0}.
    065     *
    066     * @param o1
    067     *            the object to compare
    068     * @param o2
    069     *            the object to compare to
    070     * @return the Comparable.compareTo() return code or 0 if an encoding error was caught.
    071     * @see Comparable
    072     */
    073    @Override
    074    public int compare(final Object o1, final Object o2) {
    075
    076        int compareCode = 0;
    077
    078        try {
    079            @SuppressWarnings("unchecked") // May fail with CCE if encode returns something that is not Comparable
    080            // However this was always the case.
    081            final Comparable<Comparable<?>> s1 = (Comparable<Comparable<?>>) this.stringEncoder.encode(o1);
    082            final Comparable<?> s2 = (Comparable<?>) this.stringEncoder.encode(o2);
    083            compareCode = s1.compareTo(s2);
    084        } catch (final EncoderException ee) {
    085            compareCode = 0;
    086        }
    087        return compareCode;
    088    }
    089
    090}