Source code
Description: source: package: org.apache.commons.codec, class: StringEncoderComparator

    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 *      https://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;
    021import java.util.Objects;
    022
    023/**
    024 * Compares Strings using a {@link StringEncoder}. This comparator is used to sort Strings by an encoding scheme such as Soundex, Metaphone, etc. This class can
    025 * come in handy if one need to sort Strings by an encoded form of a name such as Soundex.
    026 * <p>
    027 * This class is immutable and thread-safe.
    028 * </p>
    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 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 the StringEncoder used for comparisons.
    053     * @throws NullPointerException if the StringEncoder is null.
    054     */
    055    public StringEncoderComparator(final StringEncoder stringEncoder) {
    056        this.stringEncoder = Objects.requireNonNull(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 StringEncoder this Comparator was created with.
    061     * If an {@link EncoderException} is encountered, return {@code 0}.
    062     *
    063     * @param o1 the object to compare.
    064     * @param o2 the object to compare to.
    065     * @return The Comparable.compareTo() return code or 0 if an encoding error was caught.
    066     * @see Comparable
    067     */
    068    @Override
    069    public int compare(final Object o1, final Object o2) {
    070        int compareCode = 0;
    071        try {
    072            @SuppressWarnings("unchecked") // May fail with CCE if encode returns something that is not Comparable
    073            // However this was always the case.
    074            final Comparable<Comparable<?>> s1 = (Comparable<Comparable<?>>) stringEncoder.encode(o1);
    075            final Comparable<?> s2 = (Comparable<?>) stringEncoder.encode(o2);
    076            compareCode = s1.compareTo(s2);
    077        } catch (final EncoderException ee) {
    078            compareCode = 0;
    079        }
    080        return compareCode;
    081    }
    082}