org.apache.directory.api.asn1.util

Class BitString

java.lang.Object

org.apache.directory.api.asn1.util.BitString

public class BitString
extends Object

Implement the Bit String primitive type. A BitString is internally stored as an array of byte.

Author:

Apache Directory Project

Field Summary

Fields

Modifier and Type	Field and Description
private byte[]	bytes The string is stored in a byte array
static BitString	EMPTY_STRING A null MutableString
private int	nbBits Actual length of the bit string
private int	nbBytes Actual length of the byte array
private int	nbUnusedBits The number of unused bits in the last byte

Constructor Summary

Constructors

Constructor and Description
BitString(byte[] bytes) Creates a BitString from a byte[].
BitString(int length) Creates a BitString with a specific length (length is the number of bits).

Method Summary

Modifier and Type	Method and Description
void	clearBit(int pos) Clear a bit at a specified position.
boolean	getBit(int pos) Get the bit stored into the BitString at a specific position.
byte[]	getData() Get the representation of a BitString.
byte	getUnusedBits() Get the number of unused bits
void	setBit(int pos) Set a bit at a specified position.
void	setData(byte[] data) Set a new BitString in the BitString.
int	size()
String	toString() Return a native String representation of the BitString.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_STRING

public static final BitString EMPTY_STRING

A null MutableString

nbUnusedBits

private int nbUnusedBits

The number of unused bits in the last byte

bytes

private byte[] bytes

The string is stored in a byte array

nbBytes

private int nbBytes

Actual length of the byte array

nbBits

private int nbBits

Actual length of the bit string

Constructor Detail

BitString

public BitString(int length)

Creates a BitString with a specific length (length is the number of bits).

Parameters:

length - The BitString length (it's a number of bits)

BitString

public BitString(byte[] bytes)

Creates a BitString from a byte[]. As the first byte is the number of unused bits in the last byte, we have to ignore it.

Parameters:

bytes - The value to store. The first byte contains the number of unused bits

Method Detail

setData

public void setData(byte[] data)

Set a new BitString in the BitString. It will replace the old BitString, and reset the current length with the new one.

Parameters:

data - The string to store

getData

public byte[] getData()

Get the representation of a BitString. A first byte containing the number of unused bits is added

Returns:

A byte array which represent the BitString

getUnusedBits

public byte getUnusedBits()

Get the number of unused bits

Returns:

A byte which represent the number of unused bits

setBit

public void setBit(int pos)

Set a bit at a specified position. The bits are stored from left to right. For instance, if we have 10 bits, then they are coded as b0 b1 b2 b3 b4 b5 b6 b7 - b8 b9 x x x x x x

Parameters:

pos - The bit to set

clearBit

public void clearBit(int pos)

Clear a bit at a specified position. The bits are stored from left to right. For instance, if we have 10 bits, then they are coded as b0 b1 b2 b3 b4 b5 b6 b7 - b8 b9 x x x x x x

Parameters:

pos - The bit to clear

getBit

public boolean getBit(int pos)

Get the bit stored into the BitString at a specific position. The bits are stored from left to right, the LSB on the left and the MSB on the right.
For instance, if we have 10 bits, then they are coded as b0 b1 b2 b3 - b4 b5 b6 b7 - b8 b9 x x - x x x x

 With '1001 000x', where x is an unused bit,
       ^ ^    ^
       | |    |
       | |    |
       | |    +----- getBit(6) = 0
       | +---------- getBit(2) = 0
       +------------ getBit(0) = 1
 

Parameters:

pos - The position of the requested bit.

Returns:

true if the bit is set, false otherwise

size

public int size()

Returns:

The number of bits stored in this BitString

toString

public String toString()

Return a native String representation of the BitString.

Overrides:

toString in class Object

Returns:

A String representing the BitString