javatools.datatypes

Class CompressedString

java.lang.Object

javatools.datatypes.CompressedString

All Implemented Interfaces:

java.lang.CharSequence, java.lang.Comparable<CompressedString>

public class CompressedString
extends java.lang.Object
implements java.lang.CharSequence, java.lang.Comparable<CompressedString>

This class is part of the Java Tools (see http://mpii.de/yago-naga/javatools). It is licensed under the Creative Commons Attribution License (see http://creativecommons.org/licenses/by/3.0) by the YAGO-NAGA team (see http://mpii.de/yago-naga). This class represents an equivalence class of Strings. The equivalence class stores one prototype String, but compresses the String with 7, 6 or less bits per character (the String-class uses 16). This makes the CompressedString less memory consuming than a normal String, but possibly the original String cannot be reconstructed. The less bits you use, the less space you will consume, the less likely it will be that you can reconstruct the original String and the larger the equivalence class will be. Example:

    System.out.println(new CompressedString("How are you?",7));
    System.out.println(new CompressedString("How are you?",6));
    System.out.println(new CompressedString("How are you?",5));
    System.out.println(new CompressedString("How are you?",4));
    System.out.println(new CompressedString("How are you?",3)); 
    -->
        How are you?
        HOW ARE YOU?
        HOW ARE YOU?
        HOW@ARE@YOU
        HOG@ABE@IOEO

Field Summary

Fields

Modifier and Type	Field and Description
protected byte	BITSPERCHAR Number of bits per character
protected byte[]	data The string
protected int	length Number of characters in this CompressedString
protected int	startBit StartBit (for subsequence)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CompressedString(byte[] data, int startBit, int length) Duplicates a CompressedString (for subSequence)
	CompressedString(java.lang.CharSequence s1) Compresses a CharSequence with 6 bits
	CompressedString(java.lang.CharSequence s1, int bits) Compresses a CharSequence

Method Summary

Modifier and Type	Method and Description
int	bits() Returns the bits per character
char	charAt(int index) Returns the character at position index
int	compareTo(java.lang.CharSequence s0) 1 if this CompressedString is lexically larger than the CompressedString of the argument, else -1 or 0
int	compareTo(CompressedString s) 1 if this CompressedString is lexically larger than the the argument, else -1 or 0
boolean	equals(java.lang.Object o) Tells whether the argument (any CharSequence) is in the equivalence class of this CompressedString
int	hashCode() Returns a hash-code
int	length() Returns the number of characters in this CompressedString
static void	main(java.lang.String[] args) Test routine
java.lang.CharSequence	normalize(java.lang.CharSequence s) Normalizes (see Char.java) and upcases a CharSequence if necessary
int	size() Returns the bytes used by this CompressedString
java.lang.CharSequence	subSequence(int start, int end) Returns a subsequence of this CompressedString (without duplicating the data)
java.lang.String	toString() Tries to reconstruct the original String

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.CharSequence

chars, codePoints

Field Detail

BITSPERCHAR

protected byte BITSPERCHAR

Number of bits per character

data

protected byte[] data

The string

startBit

protected int startBit

StartBit (for subsequence)

length

protected int length

Number of characters in this CompressedString

Constructor Detail

CompressedString

protected CompressedString(byte[] data,
                           int startBit,
                           int length)

Duplicates a CompressedString (for subSequence)

CompressedString

public CompressedString(java.lang.CharSequence s1,
                        int bits)

Compresses a CharSequence

CompressedString

public CompressedString(java.lang.CharSequence s1)

Compresses a CharSequence with 6 bits

Method Detail

hashCode

public int hashCode()

Returns a hash-code

Overrides:

hashCode in class java.lang.Object

length

public int length()

Returns the number of characters in this CompressedString

Specified by:

length in interface java.lang.CharSequence

size

public int size()

Returns the bytes used by this CompressedString

bits

public int bits()

Returns the bits per character

charAt

public char charAt(int index)

Returns the character at position index

Specified by:

charAt in interface java.lang.CharSequence

equals

public boolean equals(java.lang.Object o)

Tells whether the argument (any CharSequence) is in the equivalence class of this CompressedString

Overrides:

equals in class java.lang.Object

normalize

public java.lang.CharSequence normalize(java.lang.CharSequence s)

Normalizes (see Char.java) and upcases a CharSequence if necessary

compareTo

public int compareTo(java.lang.CharSequence s0)

1 if this CompressedString is lexically larger than the CompressedString of the argument, else -1 or 0

compareTo

public int compareTo(CompressedString s)

1 if this CompressedString is lexically larger than the the argument, else -1 or 0

Specified by:

compareTo in interface java.lang.Comparable<CompressedString>

subSequence

public java.lang.CharSequence subSequence(int start,
                                          int end)

Returns a subsequence of this CompressedString (without duplicating the data)

Specified by:

subSequence in interface java.lang.CharSequence

toString

public java.lang.String toString()

Tries to reconstruct the original String

Specified by:

toString in interface java.lang.CharSequence

Overrides:

toString in class java.lang.Object

main

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

Test routine