org.apache.commons.codec.language

## Class ColognePhonetic

- java.lang.Object
- - org.apache.commons.codec.language.ColognePhonetic

- All Implemented Interfaces:
    Encoder, StringEncoder

      public class ColognePhonetic
      extends Object
      implements StringEncoder

  Encodes a string into a Cologne Phonetic value.

  Implements the Kölner Phonetik (Cologne Phonetic) algorithm issued by Hans Joachim Postel in 1969.

  The Kölner Phonetik is a phonetic algorithm which is optimized for the German language. It is related to the well-known soundex algorithm.

  ## Algorithm

  - ### Step 1:

    After preprocessing (conversion to upper case, transcription of germanic umlauts, removal of non alphabetical characters) the letters of the supplied text are replaced by their phonetic code according to the following table.

    (Source: Wikipedia (de): Kölner Phonetik -- Buchstabencodes)
    Letter | Context | Code
    --- | --- | ---
    A, E, I, J, O, U, Y |  | 0
    H |  | -
    B |  | 1
    P | not before H
    D, T | not before C, S, Z | 2
    F, V, W |  | 3
    P | before H
    G, K, Q |  | 4
    C | at onset before A, H, K, L, O, Q, R, U, X
    before A, H, K, O, Q, U, X except after S, Z
    X | not after C, K, Q | 48
    L |  | 5
    M, N |  | 6
    R |  | 7
    S, Z |  | 8
    C | after S, Z
    at onset except before A, H, K, L, O, Q, R, U, X
    not before A, H, K, O, Q, U, X
    D, T | before C, S, Z
    X | after C, K, Q

    #### Example:

    `"M`ü`ller-L`ü `denscheidt" => "MULLERLUDENSCHEIDT" => "6005507500206880022"`

  - ### Step 2:

    Collapse of all multiple consecutive code digits.

    #### Example:

    `"6005507500206880022" => "6050750206802"`

  - ### Step 3:

    Removal of all codes "0" except at the beginning. This means that two or more identical consecutive digits can occur if they occur after removing the "0" digits.

    #### Example:

    `"6050750206802" => "65752682"`

  This class is thread-safe.

  Since:
    1.5
  See Also:
    Wikipedia (de): Kölner Phonetik (in German)

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `ColognePhonetic()`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `String` | `colognePhonetic(String text)` Implements the Kölner Phonetik algorithm.
    `Object` | `encode(Object object)` Encodes an "Object" and returns the encoded content as an Object.
    `String` | `encode(String text)` Encodes a String and returns a String.
    `boolean` | `isEncodeEqual(String text1, String text2)`

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### ColognePhonetic

          public ColognePhonetic()

  - ### Method Detail

    - #### colognePhonetic

          public String colognePhonetic(String text)

      Implements the Kölner Phonetik algorithm.

      In contrast to the initial description of the algorithm, this implementation does the encoding in one pass.

      Parameters:
        `text` - The source text to encode
      Returns:
        the corresponding encoding according to the Kölner Phonetik algorithm

    - #### encode

          public Object encode(Object object)
                        throws EncoderException

      Description copied from interface: `Encoder`
      Encodes an "Object" and returns the encoded content as an Object. The Objects here may just be `byte[]` or `String`s depending on the implementation used.
      Specified by:
        `encode` in interface `Encoder`
      Parameters:
        `object` - An object to encode
      Returns:
        An "encoded" Object
      Throws:
        `EncoderException` - An encoder exception is thrown if the encoder experiences a failure condition during the encoding process.

    - #### encode

          public String encode(String text)

      Description copied from interface: `StringEncoder`
      Encodes a String and returns a String.
      Specified by:
        `encode` in interface `StringEncoder`
      Parameters:
        `text` - the String to encode
      Returns:
        the encoded String

    - #### isEncodeEqual

          public boolean isEncodeEqual(String text1,
                              String text2)

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