org.egothor.util

Class Bitmap

java.lang.Object

org.egothor.util.Bitmap

public class Bitmap
extends Object

The Bitmap object is an implementation of a bit map. Bitmap can be used for setting bits, getting states of bits. It can also be stored or loaded from a data stream.

This implementation divides the entire bit map into smaller blocks. If the block does not contain any 1-bits (the default, initial state) it is not stored in this object.

Author:

Leo Galambos

Constructor Summary

Constructors

Constructor and Description
Bitmap() The default constructor for the Bitmap object.
Bitmap(Bitmap master) Create a copy of the master.
Bitmap(DataInput is) Construct a Bitmap object using the given input stream.

Method Summary

Modifier and Type	Method and Description
Bitmap	and(Bitmap with)
long	findNextSet(long from) Return the next bit set starting at the bit of index from.
long	findNextUnset(long from) Return the next bit unset starting at the bit of index from.
byte	getBit(int num) Return the state of the specified bit (the first bit is 0).
IListReader	getIListReader(String term)
int	getSets() Returns the total number of 1-bits in the bit map.
boolean	isDirty() Test whether the Bitmap has been modified.
Bitmap	or(Bitmap with)
boolean	setBit(int num) Set the bit at index num to 1.
void	store(DataOutput os) Write this object to the given output stream.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Bitmap

public Bitmap(DataInput is)
       throws IOException

Construct a Bitmap object using the given input stream.

Parameters:

is - the input stream.

Throws:

IOException - Description of the Exception

Bitmap

public Bitmap()

The default constructor for the Bitmap object.

Bitmap

public Bitmap(Bitmap master)

Create a copy of the master.

Method Detail

setBit

public boolean setBit(int num)

Set the bit at index num to 1.

Parameters:

num - The new bit value

and

public Bitmap and(Bitmap with)

Parameters:

with -

Returns:

or

public Bitmap or(Bitmap with)

Parameters:

with -

Returns:

getBit

public byte getBit(int num)

Return the state of the specified bit (the first bit is 0).

Parameters:

num - the bit to check

Returns:

0 if the bit is off (it is set to 0).

isDirty

public boolean isDirty()

Test whether the Bitmap has been modified.

Returns:

true if it has, false otherwise

getSets

public int getSets()

Returns the total number of 1-bits in the bit map.

Returns:

the number of 1-bits

store

public void store(DataOutput os)
           throws IOException

Write this object to the given output stream.

Parameters:

os - the output stream

Throws:

IOException - Description of the Exception

getIListReader

public IListReader getIListReader(String term)

Parameters:

term -

Returns:

findNextSet

public long findNextSet(long from)

Return the next bit set starting at the bit of index from. If none bit exists, -1 is returned.

findNextUnset

public long findNextUnset(long from)

Return the next bit unset starting at the bit of index from. If none bit exists, from is returned (as obvious).