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Java > Open Source Codes > org > apache > commons > codec > language > SoundexUtils


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
17 package org.apache.commons.codec.language;
18
19 import org.apache.commons.codec.EncoderException;
20 import org.apache.commons.codec.StringEncoder;
21
22 /**
23  * Utility methods for {@link Soundex} and {@link RefinedSoundex} classes.
24  *
25  * @author Apache Software Foundation
26  * @version $Id: SoundexUtils.java,v 1.5 2004/03/17 18:31:35 ggregory Exp $
27  * @since 1.3
28  */
29 final class SoundexUtils {
30
31     /**
32      * Cleans up the input string before Soundex processing by only returning
33      * upper case letters.
34      *
35      * @param str
36      * The String to clean.
37      * @return A clean String.
38      */
39     static String JavaDoc clean(String JavaDoc str) {
40         if (str == null || str.length() == 0) {
41             return str;
42         }
43         int len = str.length();
44         char[] chars = new char[len];
45         int count = 0;
46         for (int i = 0; i < len; i++) {
47             if (Character.isLetter(str.charAt(i))) {
48                 chars[count++] = str.charAt(i);
49             }
50         }
51         if (count == len) {
52             return str.toUpperCase();
53         }
54         return new String JavaDoc(chars, 0, count).toUpperCase();
55     }
56
57     /**
58      * Encodes the Strings and returns the number of characters in the two
59      * encoded Strings that are the same.
60      * <ul>
61      * <li>For Soundex, this return value ranges from 0 through 4: 0 indicates
62      * little or no similarity, and 4 indicates strong similarity or identical
63      * values.</li>
64      * <li>For refined Soundex, the return value can be greater than 4.</li>
65      * </ul>
66      *
67      * @param encoder
68      * The encoder to use to encode the Strings.
69      * @param s1
70      * A String that will be encoded and compared.
71      * @param s2
72      * A String that will be encoded and compared.
73      * @return The number of characters in the two Soundex encoded Strings that
74      * are the same.
75      *
76      * @see #differenceEncoded(String,String)
77      * @see <a HREF="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
78      * MS T-SQL DIFFERENCE</a>
79      *
80      * @throws EncoderException
81      * if an error occurs encoding one of the strings
82      */
83     static int difference(StringEncoder encoder, String JavaDoc s1, String JavaDoc s2) throws EncoderException {
84         return differenceEncoded(encoder.encode(s1), encoder.encode(s2));
85     }
86
87     /**
88      * Returns the number of characters in the two Soundex encoded Strings that
89      * are the same.
90      * <ul>
91      * <li>For Soundex, this return value ranges from 0 through 4: 0 indicates
92      * little or no similarity, and 4 indicates strong similarity or identical
93      * values.</li>
94      * <li>For refined Soundex, the return value can be greater than 4.</li>
95      * </ul>
96      *
97      * @param es1
98      * An encoded String.
99      * @param es2
100      * An encoded String.
101      * @return The number of characters in the two Soundex encoded Strings that
102      * are the same.
103      *
104      * @see <a HREF="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_de-dz_8co5.asp">
105      * MS T-SQL DIFFERENCE</a>
106      */
107     static int differenceEncoded(String JavaDoc es1, String JavaDoc es2) {
108
109         if (es1 == null || es2 == null) {
110             return 0;
111         }
112         int lengthToMatch = Math.min(es1.length(), es2.length());
113         int diff = 0;
114         for (int i = 0; i < lengthToMatch; i++) {
115             if (es1.charAt(i) == es2.charAt(i)) {
116                 diff++;
117             }
118         }
119         return diff;
120     }
121
122 }
123
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