Class Huffman

java.lang.Object

Huffman

All Implemented Interfaces:

java.io.Serializable

public class Huffman
extends java.lang.Object
implements java.io.Serializable

Prefix codes and Huffman tree. Tree depends on source data.

Since:

1.5

Version:

0.9

Author:

Jaanus Pöial

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) class	Huffman.Node Inner class for the node of Huffman tree.

Field Summary

Fields

Modifier and Type	Field and Description
(package private) Huffman.Node[]	leaves Coding table represented as an array of leaves of the code tree
(package private) Huffman.Node	root Root of the code tree
static long	serialVersionUID serialization version id

Constructor Summary

Constructors

Constructor and Description
Huffman(byte[] original) Constructor to build the Huffman code for a given bytearray.

Method Summary

Methods

Modifier and Type	Method and Description
(package private) static byte[]	addOne(int len, byte[] code) Append bit 1 to the code (and increase the bitlength by 1).
(package private) static byte[]	addZero(int len, byte[] code) Append zero bit to the code (and increase the bitlength by 1).
int	bitLength() Length of encoded data in bits.
byte[]	decode(byte[] encodedData) Decoding the byte array using this prefixcode.
byte[]	encode(byte[] origData) Encoding the byte array using this prefixcode.
static Huffman	fromByteArray(byte[] codeTree) Deserialization of the code tree from bytearray.
static byte[]	fromFile(java.lang.String fileName) Decoding from the file.
(package private) static boolean	getBit(int index, byte[] barray) Reading a bit from the bitarray.
static void	hpack(java.lang.String sourceFile, java.lang.String packed_File) Compressing a file.
static void	hunpack(java.lang.String packed_File, java.lang.String unpackedFile) Decompressing a file.
static void	main(java.lang.String[] params) Main method.
(package private) static Huffman.Node	removeSmallest(java.util.List<Huffman.Node> nodelist) Finding a tree with minimal root frequency from the rootlist.
(package private) static void	setBit(int index, byte[] barray, boolean value) Set a bit value in bitarray.
byte[]	toByteArray() Serialization of this prefixcode.
static void	toFile(byte[] origData, java.lang.String fileName) Encoding and packing together the code tree and encoded data.
java.lang.String	toString() Conversion to string for debugging.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

public static final long serialVersionUID

serialization version id

See Also:

Constant Field Values

leaves

Huffman.Node[] leaves

Coding table represented as an array of leaves of the code tree

root

Huffman.Node root

Root of the code tree

Constructor Detail

Huffman

Huffman(byte[] original)

Constructor to build the Huffman code for a given bytearray.

Parameters:

original - source data

Method Detail

removeSmallest

static Huffman.Node removeSmallest(java.util.List<Huffman.Node> nodelist)

Finding a tree with minimal root frequency from the rootlist.

Parameters:

nodelist - queue of roots of subtrees

Returns:

node removed (root)

addZero

static byte[] addZero(int len,
             byte[] code)

Append zero bit to the code (and increase the bitlength by 1).

Parameters:

len - length of the (old) code in bits

code - old code

Returns:

new code with zero appended

addOne

static byte[] addOne(int len,
            byte[] code)

Append bit 1 to the code (and increase the bitlength by 1).

Parameters:

len - length of the (old) code in bits

code - old code

Returns:

new code with 1 appended

setBit

static void setBit(int index,
          byte[] barray,
          boolean value)

Set a bit value in bitarray.

Parameters:

index - bit index starting from 0

barray - data interpreted as an array of bits

value - value of the bit to set

getBit

static boolean getBit(int index,
             byte[] barray)

Reading a bit from the bitarray.

Parameters:

index - bit index starting from zero

barray - data interpreted as bitarray

Returns:

value of the bit

bitLength

public int bitLength()

Length of encoded data in bits.

Returns:

number of bits

toString

public java.lang.String toString()

Conversion to string for debugging.

Overrides:

toString in class java.lang.Object

Returns:

textual representation

encode

public byte[] encode(byte[] origData)

Encoding the byte array using this prefixcode.

Parameters:

origData - original data

Returns:

encoded data

decode

public byte[] decode(byte[] encodedData)

Decoding the byte array using this prefixcode.

Parameters:

encodedData - encoded data

Returns:

decoded data (hopefully identical to original)

toByteArray

public byte[] toByteArray()

Serialization of this prefixcode.

Returns:

code tree as bytearray

fromByteArray

public static Huffman fromByteArray(byte[] codeTree)

Deserialization of the code tree from bytearray.

Parameters:

codeTree - bytearray that contains the code tree

Returns:

prefixcode object

toFile

public static void toFile(byte[] origData,
          java.lang.String fileName)

Encoding and packing together the code tree and encoded data.

Parameters:

origData - original data to be encoded

fileName - output file name

fromFile

public static byte[] fromFile(java.lang.String fileName)

Decoding from the file.

Parameters:

fileName - input file name that contains code tree and encoded data

Returns:

decoded data (hopefully identical to original)

hpack

public static void hpack(java.lang.String sourceFile,
         java.lang.String packed_File)

Compressing a file.

Parameters:

sourceFile - input file name (original data to be compressed)

packed_File - output file name (contains both tree and encoded data)

hunpack

public static void hunpack(java.lang.String packed_File,
           java.lang.String unpackedFile)

Decompressing a file.

Parameters:

packed_File - input file name (contains both tree and encoded data)

unpackedFile - output file name (restored data)

main

public static void main(java.lang.String[] params)

Main method.