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 @SuppressWarnings("rawtypes")
30 // TODO ought to implement Comparator<String> but that's not possible whilst maintaining binary compatibility.
31 public class StringEncoderComparator implements Comparator {
32
33 /**
34 * Internal encoder instance.
35 */
36 private final StringEncoder stringEncoder;
37
38 /**
39 * Constructs a new instance.
40 *
41 * @deprecated Creating an instance without a {@link StringEncoder} leads to a {@link NullPointerException}. Will be
42 * removed in 2.0.
43 */
44 @Deprecated
45 public StringEncoderComparator() {
46 this.stringEncoder = null; // Trying to use this will cause things to break
47 }
48
49 /**
50 * Constructs a new instance with the given algorithm.
51 *
52 * @param stringEncoder
53 * the StringEncoder used for comparisons.
54 */
55 public StringEncoderComparator(final StringEncoder stringEncoder) {
56 this.stringEncoder = stringEncoder;
57 }
58
59 /**
60 * Compares two strings based not on the strings themselves, but on an encoding of the two strings using the
61 * StringEncoder this Comparator was created with.
62 *
63 * If an {@link EncoderException} is encountered, return {@code 0}.
64 *
65 * @param o1
66 * the object to compare
67 * @param o2
68 * the object to compare to
69 * @return the Comparable.compareTo() return code or 0 if an encoding error was caught.
70 * @see Comparable
71 */
72 @Override
73 public int compare(final Object o1, final Object o2) {
74
75 int compareCode = 0;
76
77 try {
78 @SuppressWarnings("unchecked") // May fail with CCE if encode returns something that is not Comparable
79 // However this was always the case.
80 final Comparable<Comparable<?>> s1 = (Comparable<Comparable<?>>) this.stringEncoder.encode(o1);
81 final Comparable<?> s2 = (Comparable<?>) this.stringEncoder.encode(o2);
82 compareCode = s1.compareTo(s2);
83 } catch (final EncoderException ee) {
84 compareCode = 0;
85 }
86 return compareCode;
87 }
88
89 }