
Java Platform 1.2 Beta 4 

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SUMMARY: INNER  FIELD  CONSTR  METHOD  DETAIL: FIELD  CONSTR  METHOD 
java.lang.Object  +java.util.BitSet
boolean
value. The
bits of a BitSet
are indexed by nonnegative integers.
Individual indexed bits can be examined, set, or cleared. One
BitSet
may be used to modify the contents of another
BitSet
through logical AND, logical inclusive OR, and
logical exclusive OR operations.
By default, all bits in the set initially have the value
false
.
Every bit set has a current size, which is the number of bits currently in the bit set.
Constructor Summary  
BitSet()
Creates a new bit set. 

BitSet(int nbits)
Creates a bit set whose initial size is the specified number of bits. 
Method Summary  
void  and(BitSet set)
Performs a logical AND of this target bit set with the argument bit set. 
void  andNot(BitSet set)
Clears all of the bits in this BitSet whose corresponding
bit is set in the specified BitSet . 
void  clear(int bitIndex)
The bit with index bitIndex in this BitSet
is changed to the "clear" (false ) state. 
Object  clone()
Cloning this BitSet produces a new BitSet
that is equal to it.

boolean  equals(Object obj)
Compares this object against the specified object. 
boolean  get(int bitIndex)
Returns the value of the bit with the specified index. 
int  hashCode()
Returns a hash code value for this bit set. 
int  length()
Returns the "logical size" of this BitSet : the index of
the highest set bit in the BitSet plus one. 
void  or(BitSet set)
Performs a logical OR of this bit set with the bit set argument. 
void  set(int bitIndex)
The bit with index bitIndex in this BitSet
is changed to the "set" (true ) state. 
int  size()
Returns the number of bits of space actually in use by this BitSet to represent bit values.

String  toString()
Returns a string representation of this bit set. 
void  xor(BitSet set)
Performs a logical XOR of this bit set with the bit set argument. 
Methods inherited from class java.lang.Object  
finalize , getClass , notify , notifyAll , wait , wait , wait 
Constructor Detail 
public BitSet()
false
.public BitSet(int nbits)
0
through nbits1
.
All bits are initially false
.
nbits
 the initial size of the bit set.Method Detail 
public int length()
BitSet
: the index of
the highest set bit in the BitSet
plus one.BitSet
.public void set(int bitIndex)
bitIndex
in this BitSet
is changed to the "set" (true
) state. If
bitIndex
is not smaller than the value that would be
returned by the size()
method, then
the size of this BitSet
is increased to be larger
than bitIndex
.
bitIndex
 a bit index.public void clear(int bitIndex)
bitIndex
in this BitSet
is changed to the "clear" (false
) state. If
bitIndex
is not smaller than the value that would be
returned by the size()
method, then
the size of this BitSet
is increased to be larger
than bitIndex
.
bitIndex
 the index of the bit to be cleared.public void andNot(BitSet set)
BitSet
whose corresponding
bit is set in the specified BitSet
.
s
 the BitSet
with which to mask this
BitSet
.public boolean get(int bitIndex)
true
if the bit iwth the index bitIndex
is currently set in this BitSet
; otherwise, the result
is false
.
bitIndex
 the bit index.public void and(BitSet set)
true
if and only if it both initially
had the value true
and the corresponding bit in the
bit set argument also had the value true
.
set
 a bit set.public void or(BitSet set)
true
if and only if it either already had the
value true
or the corresponding bit in the bit set
argument has the value true
.
set
 a bit set.public void xor(BitSet set)
true
if and only if one of the following
statements holds:
true
, and the
corresponding bit in the argument has the value false
.
false
, and the
corresponding bit in the argument has the value true
.
set
 a bit set.public int hashCode()
BitSet
. The algorithm used to compute it may
be described as follows.
Suppose the bits in the BitSet
were to be stored
in an array of long
integers called, say,
bits
, in such a manner that bit k
is
set in the BitSet
(for nonnegative values of
k
) if and only if the expression
((k>>6) < bits.length) && ((bits[k>>6] & (1L << (bit & 0x3F))) != 0)is true. Then the following definition of the
hashCode
method would be a correct implementation of the actual algorithm:
public synchronized int hashCode() { long h = 1234; for (int i = bits.length; i >= 0; ) { h ^= bits[i] * (i + 1); } return (int)((h >> 32) ^ h); }Note that the hash code values change if the set of bits is altered.
Overrides the hashCode
method of Object
.
public int size()
BitSet
to represent bit values.
The maximum element in the set is the size  1st element.public boolean equals(Object obj)
true
if and only if the argument is
not null
and is a Bitset
object that has
exactly the same set of bits set to true
as this bit
set. That is, for every nonnegative int
index k
,
((BitSet)obj).get(k) == this.get(k)must be true. The current sizes of the two bit sets are not compared.
Overrides the equals
method of Object
.
obj
 the object to compare with.true
if the objects are the same;
false
otherwise.size()
public Object clone()
BitSet
produces a new BitSet
that is equal to it.
The clone of the bit set is another bit set that has exactly the
same bits set to true
as this bit set and the same
current size.
Overrides the clone
method of Object
.
size()
public String toString()
BitSet
contains a bit in the set
state, the decimal representation of that index is included in
the result. Such indeces aer listed in order from lowest to
highest, separated by ",$nbsp;" (a comma and a space) and
surrounded by braces, resulting in the usual mathematical
notation for a set of integers.
Overrides the toString
method of Object
.
Example:
BitSet drPepper = new BitSet();Now
drPepper.toString()
returns "{}
".
drPepper.set(2);Now
drPepper.toString()
returns "{2}
".
drPepper.set(4); drPepper.set(10);Now
drPepper.toString()
returns "{2, 4, 10}
".

Java Platform 1.2 Beta 4 

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