Serializable
, Cloneable
public class BitSet extends Object implements Cloneable, Serializable
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 of space currently in use by the bit set. Note that the size is related to the implementation of a bit set, so it may change with implementation. The length of a bit set relates to logical length of a bit set and is defined independently of implementation.
Unless otherwise noted, passing a null parameter to any of the methods in a BitSet
will result in a NullPointerException
.
A BitSet
is not safe for multithreaded use without external synchronization.
Constructor | Description |
---|---|
BitSet() |
Creates a new bit set. |
BitSet |
Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range 0 through nbits-1 . |
Modifier and Type | Method | Description |
---|---|---|
void |
and |
Performs a logical AND of this target bit set with the argument bit set. |
void |
andNot |
Clears all of the bits in this BitSet whose corresponding bit is set in the specified BitSet . |
int |
cardinality() |
Returns the number of bits set to true in this BitSet . |
void |
clear() |
Sets all of the bits in this BitSet to false . |
void |
clear |
Sets the bit specified by the index to false . |
void |
clear |
Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to false . |
Object |
clone() |
Cloning this BitSet produces a new BitSet that is equal to it. |
boolean |
equals |
Compares this object against the specified object. |
void |
flip |
Sets the bit at the specified index to the complement of its current value. |
void |
flip |
Sets each bit from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to the complement of its current value. |
boolean |
get |
Returns the value of the bit with the specified index. |
BitSet |
get |
Returns a new BitSet composed of bits from this BitSet from fromIndex (inclusive) to toIndex (exclusive). |
int |
hashCode() |
Returns the hash code value for this bit set. |
boolean |
intersects |
Returns true if the specified BitSet has any bits set to true that are also set to true in this BitSet . |
boolean |
isEmpty() |
Returns true if this BitSet contains no bits that are set to true . |
int |
length() |
Returns the "logical size" of this BitSet : the index of the highest set bit in the BitSet plus one. |
int |
nextClearBit |
Returns the index of the first bit that is set to false that occurs on or after the specified starting index. |
int |
nextSetBit |
Returns the index of the first bit that is set to true that occurs on or after the specified starting index. |
void |
or |
Performs a logical OR of this bit set with the bit set argument. |
int |
previousClearBit |
Returns the index of the nearest bit that is set to false that occurs on or before the specified starting index. |
int |
previousSetBit |
Returns the index of the nearest bit that is set to true that occurs on or before the specified starting index. |
void |
set |
Sets the bit at the specified index to true . |
void |
set |
Sets the bit at the specified index to the specified value. |
void |
set |
Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to true . |
void |
set |
Sets the bits from the specified fromIndex (inclusive) to the specified toIndex (exclusive) to the specified value. |
int |
size() |
Returns the number of bits of space actually in use by this BitSet to represent bit values. |
IntStream |
stream() |
Returns a stream of indices for which this BitSet contains a bit in the set state. |
byte[] |
toByteArray() |
Returns a new byte array containing all the bits in this bit set. |
long[] |
toLongArray() |
Returns a new long array containing all the bits in this bit set. |
String |
toString() |
Returns a string representation of this bit set. |
static BitSet |
valueOf |
Returns a new bit set containing all the bits in the given byte array. |
static BitSet |
valueOf |
Returns a new bit set containing all the bits in the given long array. |
static BitSet |
valueOf |
Returns a new bit set containing all the bits in the given byte buffer between its position and limit. |
static BitSet |
valueOf |
Returns a new bit set containing all the bits in the given long buffer between its position and limit. |
void |
xor |
Performs a logical XOR of this bit set with the bit set argument. |
public BitSet()
false
.public BitSet(int nbits)
0
through nbits-1
. All bits are initially false
.nbits
- the initial size of the bit setNegativeArraySizeException
- if the specified initial size is negativepublic static BitSet valueOf(long[] longs)
More precisely, BitSet.valueOf(longs).get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)
for all n < 64 * longs.length
.
This method is equivalent to BitSet.valueOf(LongBuffer.wrap(longs))
.
longs
- a long array containing a little-endian representation of a sequence of bits to be used as the initial bits of the new bit setBitSet
containing all the bits in the long arraypublic static BitSet valueOf(LongBuffer lb)
More precisely, BitSet.valueOf(lb).get(n) == ((lb.get(lb.position()+n/64) & (1L<<(n%64))) != 0)
for all n < 64 * lb.remaining()
.
The long buffer is not modified by this method, and no reference to the buffer is retained by the bit set.
lb
- a long buffer containing a little-endian representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit setBitSet
containing all the bits in the buffer in the specified rangepublic static BitSet valueOf(byte[] bytes)
More precisely, BitSet.valueOf(bytes).get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)
for all n < 8 * bytes.length
.
This method is equivalent to BitSet.valueOf(ByteBuffer.wrap(bytes))
.
bytes
- a byte array containing a little-endian representation of a sequence of bits to be used as the initial bits of the new bit setBitSet
containing all the bits in the byte arraypublic static BitSet valueOf(ByteBuffer bb)
More precisely, BitSet.valueOf(bb).get(n) == ((bb.get(bb.position()+n/8) & (1<<(n%8))) != 0)
for all n < 8 * bb.remaining()
.
The byte buffer is not modified by this method, and no reference to the buffer is retained by the bit set.
bb
- a byte buffer containing a little-endian representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit setBitSet
containing all the bits in the buffer in the specified rangepublic byte[] toByteArray()
More precisely, if byte[] bytes = s.toByteArray();
then bytes.length == (s.length()+7)/8
and s.get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)
for all n < 8 * bytes.length
.
public long[] toLongArray()
More precisely, if long[] longs = s.toLongArray();
then longs.length == (s.length()+63)/64
and s.get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)
for all n < 64 * longs.length
.
public void flip(int bitIndex)
bitIndex
- the index of the bit to flipIndexOutOfBoundsException
- if the specified index is negativepublic void flip(int fromIndex, int toIndex)
fromIndex
(inclusive) to the specified toIndex
(exclusive) to the complement of its current value.fromIndex
- index of the first bit to fliptoIndex
- index after the last bit to flipIndexOutOfBoundsException
- if fromIndex
is negative, or toIndex
is negative, or fromIndex
is larger than toIndex
public void set(int bitIndex)
true
.bitIndex
- a bit indexIndexOutOfBoundsException
- if the specified index is negativepublic void set(int bitIndex, boolean value)
bitIndex
- a bit indexvalue
- a boolean value to setIndexOutOfBoundsException
- if the specified index is negativepublic void set(int fromIndex, int toIndex)
fromIndex
(inclusive) to the specified toIndex
(exclusive) to true
.fromIndex
- index of the first bit to be settoIndex
- index after the last bit to be setIndexOutOfBoundsException
- if fromIndex
is negative, or toIndex
is negative, or fromIndex
is larger than toIndex
public void set(int fromIndex, int toIndex, boolean value)
fromIndex
(inclusive) to the specified toIndex
(exclusive) to the specified value.fromIndex
- index of the first bit to be settoIndex
- index after the last bit to be setvalue
- value to set the selected bits toIndexOutOfBoundsException
- if fromIndex
is negative, or toIndex
is negative, or fromIndex
is larger than toIndex
public void clear(int bitIndex)
false
.bitIndex
- the index of the bit to be clearedIndexOutOfBoundsException
- if the specified index is negativepublic void clear(int fromIndex, int toIndex)
fromIndex
(inclusive) to the specified toIndex
(exclusive) to false
.fromIndex
- index of the first bit to be clearedtoIndex
- index after the last bit to be clearedIndexOutOfBoundsException
- if fromIndex
is negative, or toIndex
is negative, or fromIndex
is larger than toIndex
public void clear()
false
.public boolean get(int bitIndex)
true
if the bit with the index bitIndex
is currently set in this BitSet
; otherwise, the result is false
.bitIndex
- the bit indexIndexOutOfBoundsException
- if the specified index is negativepublic BitSet get(int fromIndex, int toIndex)
BitSet
composed of bits from this BitSet
from fromIndex
(inclusive) to toIndex
(exclusive).fromIndex
- index of the first bit to includetoIndex
- index after the last bit to includeBitSet
from a range of this BitSet
IndexOutOfBoundsException
- if fromIndex
is negative, or toIndex
is negative, or fromIndex
is larger than toIndex
public int nextSetBit(int fromIndex)
true
that occurs on or after the specified starting index. If no such bit exists then -1
is returned. To iterate over the true
bits in a BitSet
, use the following loop:
for (int i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) {
// operate on index i here
if (i == Integer.MAX_VALUE) {
break; // or (i+1) would overflow
}
}
fromIndex
- the index to start checking from (inclusive)-1
if there is no such bitIndexOutOfBoundsException
- if the specified index is negativepublic int nextClearBit(int fromIndex)
false
that occurs on or after the specified starting index.fromIndex
- the index to start checking from (inclusive)IndexOutOfBoundsException
- if the specified index is negativepublic int previousSetBit(int fromIndex)
true
that occurs on or before the specified starting index. If no such bit exists, or if -1
is given as the starting index, then -1
is returned. To iterate over the true
bits in a BitSet
, use the following loop:
for (int i = bs.length(); (i = bs.previousSetBit(i-1)) >= 0; ) {
// operate on index i here
}
fromIndex
- the index to start checking from (inclusive)-1
if there is no such bitIndexOutOfBoundsException
- if the specified index is less than -1
public int previousClearBit(int fromIndex)
false
that occurs on or before the specified starting index. If no such bit exists, or if -1
is given as the starting index, then -1
is returned.fromIndex
- the index to start checking from (inclusive)-1
if there is no such bitIndexOutOfBoundsException
- if the specified index is less than -1
public int length()
BitSet
: the index of the highest set bit in the BitSet
plus one. Returns zero if the BitSet
contains no set bits.BitSet
public boolean isEmpty()
BitSet
contains no bits that are set to true
.BitSet
is emptypublic boolean intersects(BitSet set)
BitSet
has any bits set to true
that are also set to true
in this BitSet
.set
- BitSet
to intersect withBitSet
intersects the specified BitSet
public int cardinality()
true
in this BitSet
.true
in this BitSet
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 setpublic 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 setpublic 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 setpublic void andNot(BitSet set)
BitSet
whose corresponding bit is set in the specified BitSet
.set
- the BitSet
with which to mask this BitSet
public int hashCode()
BitSet
. The hash code is defined to be the result of the following calculation:
public int hashCode() {
long h = 1234;
long[] words = toLongArray();
for (int i = words.length; --i >= 0; )
h ^= words[i] * (i + 1);
return (int)((h >> 32) ^ h);
}
Note that the hash code changes if the set of bits is altered.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.
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.public String toString()
BitSet
contains a bit in the set state, the decimal representation of that index is included in the result. Such indices are listed in order from lowest to highest, separated by ", " (a comma and a space) and surrounded by braces, resulting in the usual mathematical notation for a set of integers. 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}
".public IntStream stream()
BitSet
contains a bit in the set state. The indices are returned in order, from lowest to highest. The size of the stream is the number of bits in the set state, equal to the value returned by the cardinality()
method. The stream binds to this bit set when the terminal stream operation commences (specifically, the spliterator for the stream is late-binding). If the bit set is modified during that operation then the result is undefined.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/BitSet.html