Package org.apache.commons.text

Class AlphabetConverter

java.lang.Object

org.apache.commons.text.AlphabetConverter

public final class AlphabetConverter
extends Object

Convert from one alphabet to another, with the possibility of leaving certain characters unencoded.

The target and do not encode languages must be in the Unicode BMP, but the source language does not.

The encoding will all be of a fixed length, except for the 'do not encode' chars, which will be of length 1

Sample usage

 Character[] originals;   // a, b, c, d
 Character[] encoding;    // 0, 1, d
 Character[] doNotEncode; // d

 AlphabetConverter ac = AlphabetConverter.createConverterFromChars(originals,
 encoding, doNotEncode);

 ac.encode("a");    // 00
 ac.encode("b");    // 01
 ac.encode("c");    // 0d
 ac.encode("d");    // d
 ac.encode("abcd"); // 00010dd
 

#ThreadSafe# AlphabetConverter class methods are thread-safe as they do not change internal state.

Since:

1.0

Method Summary

Modifier and Type	Method	Description
static AlphabetConverter	createConverter(Integer[] original, Integer[] encoding, Integer[] doNotEncode)	Creates an alphabet converter, for converting from the original alphabet, to the encoded alphabet, while leaving the characters in doNotEncode as they are (if possible).
static AlphabetConverter	createConverterFromChars(Character[] original, Character[] encoding, Character[] doNotEncode)	Creates an alphabet converter, for converting from the original alphabet, to the encoded alphabet, while leaving the characters in doNotEncode as they are (if possible).
static AlphabetConverter	createConverterFromMap(Map<Integer,String> originalToEncoded)	Creates a new converter from a map.
String	decode(String encoded)	Decodes a given string.
String	encode(String original)	Encodes a given string.
boolean	equals(Object obj)
int	getEncodedCharLength()	Gets the length of characters in the encoded alphabet that are necessary for each character in the original alphabet.
Map<Integer,String>	getOriginalToEncoded()	Gets the mapping from integer code point of source language to encoded string.
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Method Detail

createConverter

public static AlphabetConverter createConverter(Integer[] original,
                                                Integer[] encoding,
                                                Integer[] doNotEncode)

Creates an alphabet converter, for converting from the original alphabet, to the encoded alphabet, while leaving the characters in doNotEncode as they are (if possible).

Duplicate letters in either original or encoding will be ignored.

Parameters:

original - an array of ints representing the original alphabet in code points

encoding - an array of ints representing the alphabet to be used for encoding, in code points

doNotEncode - an array of ints representing the chars to be encoded using the original alphabet - every char here must appear in both the previous params

Returns:

The AlphabetConverter

Throws:

IllegalArgumentException - if an AlphabetConverter cannot be constructed

createConverterFromChars

public static AlphabetConverter createConverterFromChars(Character[] original,
                                                         Character[] encoding,
                                                         Character[] doNotEncode)

Creates an alphabet converter, for converting from the original alphabet, to the encoded alphabet, while leaving the characters in doNotEncode as they are (if possible).

Duplicate letters in either original or encoding will be ignored.

Parameters:

original - an array of chars representing the original alphabet

encoding - an array of chars representing the alphabet to be used for encoding

doNotEncode - an array of chars to be encoded using the original alphabet - every char here must appear in both the previous params

Returns:

The AlphabetConverter

Throws:

IllegalArgumentException - if an AlphabetConverter cannot be constructed

createConverterFromMap

public static AlphabetConverter createConverterFromMap(Map<Integer,String> originalToEncoded)

Creates a new converter from a map.

Parameters:

originalToEncoded - a map returned from getOriginalToEncoded()

Returns:

The reconstructed AlphabetConverter

See Also:

getOriginalToEncoded()

decode

public String decode(String encoded)
              throws UnsupportedEncodingException

Decodes a given string.

Parameters:

encoded - a string that has been encoded using this AlphabetConverter

Returns:

The decoded string, null if the given string is null

Throws:

UnsupportedEncodingException - if unexpected characters that cannot be handled are encountered

encode

public String encode(String original)
              throws UnsupportedEncodingException

Encodes a given string.

Parameters:

original - the string to be encoded

Returns:

The encoded string, null if the given string is null

Throws:

UnsupportedEncodingException - if chars that are not supported are encountered

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

getEncodedCharLength

public int getEncodedCharLength()

Gets the length of characters in the encoded alphabet that are necessary for each character in the original alphabet.

Returns:

The length of the encoded char

getOriginalToEncoded

public Map<Integer,String> getOriginalToEncoded()

Gets the mapping from integer code point of source language to encoded string. Use to reconstruct converter from serialized map.

Returns:

The original map

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object