Package blbutil

Class BitArray

java.lang.Object

blbutil.BitArray

public class BitArray
extends java.lang.Object

Interface BitArray represents a mutable sequence of bits with a fixed length.

Instances of BitArray are not thread-safe.

Constructor Summary

Constructors

Constructor	Description
BitArray(int size)	Constructs a BitArray instance with the specified size and having all bits set to 0 (unset).
BitArray(long[] values, int size)	Constructs a BitArray instance from the specified values.
BitArray(BitArray bitList)	Constructs a new BitArray instance with the same sequence of bits and the same size as the specified BitArray.

Method Summary

Modifier and Type	Method	Description
void	clear()	Clears all bits.
void	clear(int index)	Clears the specified bit.
void	copyFrom(BitArray src, int from, int to)	Replaced the specified bits in this Bitlist with the corresponding bits in the specified BitArray.
boolean	equal(BitArray other, int from, int to)	Returns true if this Bitlist and the specified BitArray have identical sequences of bits for the specified indices, and returns false otherwise.
static boolean	equals(BitArray a, BitArray b)	Returns true if the specified BitArray objects represent identical bit sequences having the same size, and returns false otherwise.
boolean	get(int index)	Returns the specified bit as a boolean value.
int	getAsInt(int index)	Returns the specified bit as a int value.
int	hash(int from, int to)	Returns a hash code for the specified bits in this Bitlist
BitArray	restrict(int from, int to)	Returns a new BitArray of size (from - to) that is a copy of the specified bit indices of this BitArray.
void	set(int index)	Sets the specified bit.
int	size()	Returns the number of bits in this BitArray.
static void	swapBits(BitArray a, BitArray b, int from, int to)	Swaps the specified bits of the two specified Bitlist objects.
long[]	toLongArray()	Returns this BitArray as a long array.
java.lang.String	toString()	Returns a string representation of this BitArray.

Methods inherited from class java.lang.Object

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

Constructor Detail

BitArray

public BitArray(int size)

Constructs a BitArray instance with the specified size and having all bits set to 0 (unset).

Parameters:

size - the number of bits

Throws:

java.lang.IllegalArgumentException - if size < 0

BitArray

public BitArray(long[] values,
                int size)

Constructs a BitArray instance from the specified values.

Parameters:

values - a sequence of bits

size - the number of bits

Throws:

java.lang.IllegalArgumentException - if size < 0

java.lang.IllegalArgumentException - if values.length != (size + Long.SIZE - 1) / Long.SIZE

java.lang.NullPointerException - if values == null

BitArray

public BitArray(BitArray bitList)

Constructs a new BitArray instance with the same sequence of bits and the same size as the specified BitArray.

Parameters:

bitList - a sequence of bits to be copied

Throws:

java.lang.NullPointerException - if bitList == null

Method Detail

size

public int size()

Returns the number of bits in this BitArray.

Returns:

the number of bits in this BitArray

get

public boolean get(int index)

Returns the specified bit as a boolean value. A 1 bit returns true and a 0 bit returns false.

Parameters:

index - a bit index

Returns:

the specified bit as a boolean value.

Throws:

java.lang.IndexOutOfBoundsException - if index < 0 || index >= this.size()

getAsInt

public int getAsInt(int index)

Returns the specified bit as a int value.

Parameters:

index - a bit index

Returns:

the specified bit as a int value.

Throws:

java.lang.IndexOutOfBoundsException - if index < 0 || index >= this.size()

set

public void set(int index)

Sets the specified bit.

Parameters:

index - a bit index

Throws:

java.lang.IndexOutOfBoundsException - if index < 0 || index >= this.size()

clear

public void clear(int index)

Clears the specified bit.

Parameters:

index - a bit index

Throws:

java.lang.IndexOutOfBoundsException - if index < 0 || index >= this.size()

clear

public void clear()

Clears all bits.

restrict

public BitArray restrict(int from,
                         int to)

Returns a new BitArray of size (from - to) that is a copy of the specified bit indices of this BitArray.

Parameters:

from - the first bit to be copied (inclusive)

to - the last bit to be copied (exclusive)

Returns:

a new BitArray of size (from - to) that is a copy of the specified bit indices of this BitArray

Throws:

java.lang.IndexOutOfBoundsException - if from < 0 || from > to || to > this.size

copyFrom

public void copyFrom(BitArray src,
                     int from,
                     int to)

Replaced the specified bits in this Bitlist with the corresponding bits in the specified BitArray.

Parameters:

src - the BitArray to be copied from

from - the first bit to be copied (inclusive)

to - the last bit to be copied (exclusive)

Throws:

java.lang.IndexOutOfBoundsException - if from < 0 || from > to || to > this.size || to > src.size()

java.lang.NullPointerException - if src == null

hash

public int hash(int from,
                int to)

Returns a hash code for the specified bits in this Bitlist

Parameters:

from - the first bit (inclusive)

to - the last bit (exclusive)

Returns:

a hash code for the specified bits in this Bitlist

Throws:

java.lang.IndexOutOfBoundsException - if from < 0 || from > to || to > this.size

swapBits

public static void swapBits(BitArray a,
                            BitArray b,
                            int from,
                            int to)

Swaps the specified bits of the two specified Bitlist objects.

Parameters:

a - the first BitArray

b - the second BitArray

from - the first bit to be copied (inclusive)

to - the last bit to be copied (exclusive)

Throws:

java.lang.IllegalArgumentException - if s.size() != b.size()

java.lang.IndexOutOfBoundsException - if from < 0 || from > to || to > a.size()

java.lang.NullPointerException - if a == null || b == null

equal

public boolean equal(BitArray other,
                     int from,
                     int to)

Returns true if this Bitlist and the specified BitArray have identical sequences of bits for the specified indices, and returns false otherwise. Returns true if (from == to) && (0 <= from) && (from < other.size()).

Parameters:

other - the BitArray to be compared with this for equality.

from - the first bit to be compared (inclusive)

to - the last bit to be compared (exclusive)

Returns:

true if this Bitlist and the specified BitArray have identical sequences of bits for the specified indices.

Throws:

java.lang.IndexOutOfBoundsException - if from < 0 || from > to || to > this.size || to > other.size()

java.lang.NullPointerException - if other == null

toLongArray

public long[] toLongArray()

Returns this BitArray as a long array.

Returns:

this BitArray as a long array

toString

public java.lang.String toString()

Returns a string representation of this BitArray. The exact details of the representation are unspecified and subject to change.

Overrides:

toString in class java.lang.Object

Returns:

a string representation of this BitArray.

equals

public static boolean equals(BitArray a,
                             BitArray b)

Returns true if the specified BitArray objects represent identical bit sequences having the same size, and returns false otherwise.

Parameters:

a - a sequence of long values

b - a sequence of long values

Returns:

true if the specified BitArray objects represent identical bit sequences having the same size

Throws:

java.lang.NullPointerException - if a == null || b == null