1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.codec;
19
20 import java.util.Comparator;
21
22 /**
23 * Compares Strings using a {@link StringEncoder}. This comparator is used to sort Strings by an encoding scheme such as
24 * Soundex, Metaphone, etc. This class can come in handy if one need to sort Strings by an encoded form of a name such
25 * as Soundex.
26 *
27 * <p>This class is immutable and thread-safe.</p>
28 *
29 * @version $Id: StringEncoderComparator.java 1468177 2013-04-15 18:35:15Z ggregory $
30 */
31 @SuppressWarnings("rawtypes")
32 // TODO ought to implement Comparator<String> but that's not possible whilst maintaining binary compatibility.
33 public class StringEncoderComparator implements Comparator {
34
35 /**
36 * Internal encoder instance.
37 */
38 private final StringEncoder stringEncoder;
39
40 /**
41 * Constructs a new instance.
42 *
43 * @deprecated Creating an instance without a {@link StringEncoder} leads to a {@link NullPointerException}. Will be
44 * removed in 2.0.
45 */
46 @Deprecated
47 public StringEncoderComparator() {
48 this.stringEncoder = null; // Trying to use this will cause things to break
49 }
50
51 /**
52 * Constructs a new instance with the given algorithm.
53 *
54 * @param stringEncoder
55 * the StringEncoder used for comparisons.
56 */
57 public StringEncoderComparator(final StringEncoder stringEncoder) {
58 this.stringEncoder = stringEncoder;
59 }
60
61 /**
62 * Compares two strings based not on the strings themselves, but on an encoding of the two strings using the
63 * StringEncoder this Comparator was created with.
64 *
65 * If an {@link EncoderException} is encountered, return <code>0</code>.
66 *
67 * @param o1
68 * the object to compare
69 * @param o2
70 * the object to compare to
71 * @return the Comparable.compareTo() return code or 0 if an encoding error was caught.
72 * @see Comparable
73 */
74 @Override
75 public int compare(final Object o1, final Object o2) {
76
77 int compareCode = 0;
78
79 try {
80 @SuppressWarnings("unchecked") // May fail with CCE if encode returns something that is not Comparable
81 // However this was always the case.
82 final Comparable<Comparable<?>> s1 = (Comparable<Comparable<?>>) this.stringEncoder.encode(o1);
83 final Comparable<?> s2 = (Comparable<?>) this.stringEncoder.encode(o2);
84 compareCode = s1.compareTo(s2);
85 } catch (final EncoderException ee) {
86 compareCode = 0;
87 }
88 return compareCode;
89 }
90
91 }