StringEncoderComparator.java revision 417f3b92ba4549b2f22340e3107d869d2b9c5bb8 
1/*
2 * Copyright 2001-2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package org.apache.commons.codec;
18
19import java.util.Comparator;
20
21/**
22 * Strings are comparable, and this comparator allows
23 * you to configure it with an instance of a class
24 * which implements StringEncoder.  This comparator
25 * is used to sort Strings by an encoding scheme such
26 * as Soundex, Metaphone, etc.  This class can come in
27 * handy if one need to sort Strings by an encoded
28 * form of a name such as Soundex.
29 *
30 * @author Apache Software Foundation
31 * @version $Id: StringEncoderComparator.java,v 1.14 2004/06/21 23:24:17 ggregory Exp $
32 */
33public class StringEncoderComparator implements Comparator {
34
35    /**
36     * Internal encoder instance.
37     */
38    private StringEncoder stringEncoder;
39
40    /**
41     * Constructs a new instance.
42     */
43    public StringEncoderComparator() {
44        // no init.
45    }
46
47    /**
48     * Constructs a new instance with the given algorithm.
49     * @param stringEncoder the StringEncoder used for comparisons.
50     */
51    public StringEncoderComparator(StringEncoder stringEncoder) {
52        this.stringEncoder = stringEncoder;
53    }
54
55    /**
56     * Compares two strings based not on the strings
57     * themselves, but on an encoding of the two
58     * strings using the StringEncoder this Comparator
59     * was created with.
60     *
61     * If an {@link EncoderException} is encountered, return <code>0</code>.
62     *
63     * @param o1 the object to compare
64     * @param o2 the object to compare to
65     * @return the Comparable.compareTo() return code or 0 if an encoding error was caught.
66     * @see Comparable
67     */
68    public int compare(Object o1, Object o2) {
69
70        int compareCode = 0;
71
72        try {
73            Comparable s1 = (Comparable) ((Encoder) this.stringEncoder).encode(o1);
74            Comparable s2 = (Comparable) ((Encoder) this.stringEncoder).encode(o2);
75            compareCode = s1.compareTo(s2);
76        }
77        catch (EncoderException ee) {
78            compareCode = 0;
79        }
80        return compareCode;
81    }
82
83}
84