Class Metaphone

java.lang.Object
org.apache.commons.codec.language.Metaphone
All Implemented Interfaces:
Encoder, StringEncoder

public class Metaphone extends 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:

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 for maximum code length 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.

  • Field Details

    • VOWELS

      private static final String VOWELS
      Five values in the English language
      See Also:
    • FRONTV

      private static final String FRONTV
      Variable used in Metaphone algorithm
      See Also:
    • VARSON

      private static final String VARSON
      Variable used in Metaphone algorithm
      See Also:
    • maxCodeLen

      private int maxCodeLen
      The max code length for metaphone is 4
  • Constructor Details

    • Metaphone

      public Metaphone()
  • Method Details

    • metaphone

      public String metaphone(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(StringBuilder string, int index)
    • isPreviousChar

      private boolean isPreviousChar(StringBuilder string, int index, char c)
    • isNextChar

      private boolean isNextChar(StringBuilder string, int index, char c)
    • regionMatch

      private boolean regionMatch(StringBuilder string, int index, String test)
    • isLastChar

      private boolean isLastChar(int wdsz, int n)
    • encode

      public Object encode(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 String encode(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(String str1, 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