org.apache.commons.codec.language

Class Metaphone

java.lang.Object

org.apache.commons.codec.language.Metaphone

All Implemented Interfaces:

Encoder, StringEncoder

public class Metaphone
extends java.lang.Object
implements StringEncoder

Encodes a string into a Metaphone value.

Initial Java implementation by William B. Brogden. December, 1997. Permission given by wbrogden for code to be used anywhere.

Hanging on the Metaphone by Lawrence Philips in Computer Language of Dec. 1990, p 39.

Note, that this does not match the algorithm that ships with PHP, or the algorithm found in the Perl implementations:

• Text:Metaphone-1.96 (broken link 4/30/2013)
• Text:Metaphone-1.96 (link checked 4/30/2013)

They have had undocumented changes from the originally published algorithm. For more information, see CODEC-57.

This class is conditionally thread-safe. The instance field maxCodeLen is mutable setMaxCodeLen(int) but is not volatile, and accesses are not synchronized. If an instance of the class is shared between threads, the caller needs to ensure that suitable synchronization is used to ensure safe publication of the value between threads, and must not invoke setMaxCodeLen(int) after initial setup.

Version:

$Id: Metaphone.java 1619948 2014-08-22 22:53:55Z ggregory $

Field Summary

Fields

Modifier and Type	Field and Description
private static java.lang.String	FRONTV Variable used in Metaphone algorithm
private int	maxCodeLen The max code length for metaphone is 4
private static java.lang.String	VARSON Variable used in Metaphone algorithm
private static java.lang.String	VOWELS Five values in the English language

Constructor Summary

Constructors

Constructor and Description
Metaphone() Creates an instance of the Metaphone encoder

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	encode(java.lang.Object obj) Encodes an Object using the metaphone algorithm.
java.lang.String	encode(java.lang.String str) Encodes a String using the Metaphone algorithm.
int	getMaxCodeLen() Returns the maxCodeLen.
private boolean	isLastChar(int wdsz, int n)
boolean	isMetaphoneEqual(java.lang.String str1, java.lang.String str2) Tests is the metaphones of two strings are identical.
private boolean	isNextChar(java.lang.StringBuilder string, int index, char c)
private boolean	isPreviousChar(java.lang.StringBuilder string, int index, char c)
private boolean	isVowel(java.lang.StringBuilder string, int index)
java.lang.String	metaphone(java.lang.String txt) Find the metaphone value of a String.
private boolean	regionMatch(java.lang.StringBuilder string, int index, java.lang.String test)
void	setMaxCodeLen(int maxCodeLen) Sets the maxCodeLen.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

VOWELS

private static final java.lang.String VOWELS

Five values in the English language

See Also:

Constant Field Values

FRONTV

private static final java.lang.String FRONTV

Variable used in Metaphone algorithm

See Also:

Constant Field Values

VARSON

private static final java.lang.String VARSON

Variable used in Metaphone algorithm

See Also:

Constant Field Values

maxCodeLen

private int maxCodeLen

The max code length for metaphone is 4

Constructor Detail

Metaphone

public Metaphone()

Creates an instance of the Metaphone encoder

Method Detail

metaphone

public java.lang.String metaphone(java.lang.String txt)

Find the metaphone value of a String. This is similar to the soundex algorithm, but better at finding similar sounding words. All input is converted to upper case. Limitations: Input format is expected to be a single ASCII word with only characters in the A - Z range, no punctuation or numbers.

Parameters:

txt - String to find the metaphone code for

Returns:

A metaphone code corresponding to the String supplied

isVowel

private boolean isVowel(java.lang.StringBuilder string,
              int index)

isPreviousChar

private boolean isPreviousChar(java.lang.StringBuilder string,
                     int index,
                     char c)

isNextChar

private boolean isNextChar(java.lang.StringBuilder string,
                 int index,
                 char c)

regionMatch

private boolean regionMatch(java.lang.StringBuilder string,
                  int index,
                  java.lang.String test)

isLastChar

private boolean isLastChar(int wdsz,
                 int n)

encode

public java.lang.Object encode(java.lang.Object obj)
                        throws EncoderException

Encodes an Object using the metaphone algorithm. This method is provided in order to satisfy the requirements of the Encoder interface, and will throw an EncoderException if the supplied object is not of type java.lang.String.

Specified by:

encode in interface Encoder

Parameters:

obj - Object to encode

Returns:

An object (or type java.lang.String) containing the metaphone code which corresponds to the String supplied.

Throws:

EncoderException - if the parameter supplied is not of type java.lang.String

encode

public java.lang.String encode(java.lang.String str)

Encodes a String using the Metaphone algorithm.

Specified by:

encode in interface StringEncoder

Parameters:

str - String object to encode

Returns:

The metaphone code corresponding to the String supplied

isMetaphoneEqual

public boolean isMetaphoneEqual(java.lang.String str1,
                       java.lang.String str2)

Tests is the metaphones of two strings are identical.

Parameters:

str1 - First of two strings to compare

str2 - Second of two strings to compare

Returns:

true if the metaphones of these strings are identical, false otherwise.

getMaxCodeLen

public int getMaxCodeLen()

Returns the maxCodeLen.

Returns:

int

setMaxCodeLen

public void setMaxCodeLen(int maxCodeLen)

Sets the maxCodeLen.

Parameters:

maxCodeLen - The maxCodeLen to set