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| java.lang.Object
 java.util.BitSet
| BitSet | | public class BitSet implements Cloneable,java.io.Serializable(Code) | | This class implements a vector of bits that grows as needed. Each
component of the bit set has a
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.
author:
Arthur van Hoff
author:
Michael McCloskey
author:
Martin Buchholz
version:
1.74, 06/12/07
since:
JDK1.0 |
| Constructor Summary | |
| public | BitSet()
Creates a new bit set. | | public | BitSet(int nbits)
Creates a bit set whose initial size is large enough to explicitly
represent bits with indices in the range
0 through
nbits-1 . |
| Method Summary | |
| public void | and(BitSet set)
Performs a logical AND of this target bit set with the
argument bit set. | | public void | andNot(BitSet set)
Clears all of the bits in this
BitSet whose corresponding
bit is set in the specified
BitSet . | | public int | cardinality()
Returns the number of bits set to
true in this
BitSet . | | public void | clear(int bitIndex)
Sets the bit specified by the index to
false . | | public void | clear(int fromIndex, int toIndex)
Sets the bits from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to
false . | | public void | clear()
Sets all of the bits in this BitSet to
false . | | public Object | clone()
Cloning this
BitSet produces a new
BitSet that is equal to it. | | public boolean | equals(Object obj)
Compares this object against the specified object.
The result is
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. | | public void | flip(int bitIndex)
Sets the bit at the specified index to the complement of its
current value. | | public void | flip(int fromIndex, int toIndex)
Sets each bit from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to the complement of its current
value. | | public boolean | get(int bitIndex)
Returns the value of the bit with the specified index. | | public BitSet | get(int fromIndex, int toIndex)
Returns a new
BitSet composed of bits from this
BitSet from
fromIndex (inclusive) to
toIndex (exclusive). | | public int | hashCode()
| | public boolean | intersects(BitSet set)
Returns true if the specified
BitSet has any bits set to
true that are also set to
true in this
BitSet . | | public boolean | isEmpty()
Returns true if this
BitSet contains no bits that are set
to
true . | | public int | length()
Returns the "logical size" of this
BitSet : the index of
the highest set bit in the
BitSet plus one. | | public int | nextClearBit(int fromIndex)
Returns the index of the first bit that is set to
false that occurs on or after the specified starting index. | | public int | nextSetBit(int fromIndex)
Returns the index of the first bit that is set to
true that occurs on or after the specified starting index. | | public void | or(BitSet set)
Performs a logical OR of this bit set with the bit set
argument. | | public void | set(int bitIndex)
Sets the bit at the specified index to
true . | | public void | set(int bitIndex, boolean value)
Sets the bit at the specified index to the specified value. | | public void | set(int fromIndex, int toIndex)
Sets the bits from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to
true . | | public void | set(int fromIndex, int toIndex, boolean value)
Sets the bits from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to the specified value. | | public int | size()
Returns the number of bits of space actually in use by this
BitSet to represent bit values. | | public byte[] | toByteArray()
Returns a new byte array containing all the bits in this bit set. | | public long[] | toLongArray()
Returns a new long array containing all the bits in this bit set. | | public String | toString()
| | public static BitSet | valueOf(long[] longs)
Returns a new bit set containing all the bits in the given long array. | | public static BitSet | valueOf(LongBuffer lb)
Returns a new bit set containing all the bits in the given long
buffer between its position and limit. | | public static BitSet | valueOf(byte[] bytes)
Returns a new bit set containing all the bits in the given byte array. | | public static BitSet | valueOf(ByteBuffer bb)
Returns a new bit set containing all the bits in the given byte
buffer between its position and limit. | | public void | xor(BitSet set)
Performs a logical XOR of this bit set with the bit set
argument. |
| BitSet | | public BitSet()(Code) | | Creates a new bit set. All bits are initially
false .
|
| BitSet | | public BitSet(int nbits)(Code) | | Creates a bit set whose initial size is large enough to explicitly
represent bits with indices in the range
0 through
nbits-1 . All bits are initially
false .
Parameters:
nbits - the initial size of the bit set
throws:
NegativeArraySizeException - if the specified initial sizeis negative |
| and | | public void and(BitSet set)(Code) | | Performs a logical AND of this target bit set with the
argument bit set. This bit set is modified so that each bit in it
has the value
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 .
Parameters:
set - a bit set |
| andNot | | public void andNot(BitSet set)(Code) | | Clears all of the bits in this
BitSet whose corresponding
bit is set in the specified
BitSet .
Parameters:
set - the BitSet with which to mask this BitSet
since:
1.2 |
| cardinality | | public int cardinality()(Code) | | Returns the number of bits set to
true in this
BitSet .
the number of bits set to true in this BitSet
since:
1.4 |
| clear | | public void clear(int bitIndex)(Code) | | Sets the bit specified by the index to
false .
Parameters:
bitIndex - the index of the bit to be cleared
throws:
IndexOutOfBoundsException - if the specified index is negative
since:
JDK1.0 |
| clear | | public void clear(int fromIndex, int toIndex)(Code) | | Sets the bits from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to
false .
Parameters:
fromIndex - index of the first bit to be cleared
Parameters:
toIndex - index after the last bit to be cleared
throws:
IndexOutOfBoundsException - if fromIndex is negative,or toIndex is negative, or fromIndex islarger than toIndex
since:
1.4 |
| clear | | public void clear()(Code) | | Sets all of the bits in this BitSet to
false .
since:
1.4 |
| clone | | public Object clone()(Code) | | Cloning this
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.
a clone of this bit set
See Also: BitSet.size() |
| equals | | public boolean equals(Object obj)(Code) | | Compares this object against the specified object.
The result is
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.
Parameters:
obj - the object to compare with true if the objects are the same; false otherwise
See Also: BitSet.size() |
| flip | | public void flip(int bitIndex)(Code) | | Sets the bit at the specified index to the complement of its
current value.
Parameters:
bitIndex - the index of the bit to flip
throws:
IndexOutOfBoundsException - if the specified index is negative
since:
1.4 |
| flip | | public void flip(int fromIndex, int toIndex)(Code) | | Sets each bit from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to the complement of its current
value.
Parameters:
fromIndex - index of the first bit to flip
Parameters:
toIndex - index after the last bit to flip
throws:
IndexOutOfBoundsException - if fromIndex is negative,or toIndex is negative, or fromIndex islarger than toIndex
since:
1.4 |
| get | | public boolean get(int bitIndex)(Code) | | Returns the value of the bit with the specified index. The value
is
true if the bit with the index
bitIndex is currently set in this
BitSet ; otherwise, the result
is
false .
Parameters:
bitIndex - the bit index the value of the bit with the specified index
throws:
IndexOutOfBoundsException - if the specified index is negative |
| get | | public BitSet get(int fromIndex, int toIndex)(Code) | | Returns a new
BitSet composed of bits from this
BitSet from
fromIndex (inclusive) to
toIndex (exclusive).
Parameters:
fromIndex - index of the first bit to include
Parameters:
toIndex - index after the last bit to include a new BitSet from a range of this BitSet
throws:
IndexOutOfBoundsException - if fromIndex is negative,or toIndex is negative, or fromIndex islarger than toIndex
since:
1.4 |
| hashCode | | public int hashCode()(Code) | | |
| intersects | | public boolean intersects(BitSet set)(Code) | | Returns true if the specified
BitSet has any bits set to
true that are also set to
true in this
BitSet .
Parameters:
set - BitSet to intersect with boolean indicating whether this BitSet intersectsthe specified BitSet
since:
1.4 |
| isEmpty | | public boolean isEmpty()(Code) | | Returns true if this
BitSet contains no bits that are set
to
true .
boolean indicating whether this BitSet is empty
since:
1.4 |
| length | | public int length()(Code) | | Returns the "logical size" of this
BitSet : the index of
the highest set bit in the
BitSet plus one. Returns zero
if the
BitSet contains no set bits.
the logical size of this BitSet
since:
1.2 |
| nextClearBit | | public int nextClearBit(int fromIndex)(Code) | | Returns the index of the first bit that is set to
false that occurs on or after the specified starting index.
Parameters:
fromIndex - the index to start checking from (inclusive) the index of the next clear bit
throws:
IndexOutOfBoundsException - if the specified index is negative
since:
1.4 |
| nextSetBit | | public int nextSetBit(int fromIndex)(Code) | | Returns the index of the first bit that is set to
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
}
Parameters:
fromIndex - the index to start checking from (inclusive) the index of the next set bit
throws:
IndexOutOfBoundsException - if the specified index is negative
since:
1.4 |
| or | | public void or(BitSet set)(Code) | | Performs a logical OR of this bit set with the bit set
argument. This bit set is modified so that a bit in it has the
value
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 .
Parameters:
set - a bit set |
| set | | public void set(int bitIndex)(Code) | | Sets the bit at the specified index to
true .
Parameters:
bitIndex - a bit index
throws:
IndexOutOfBoundsException - if the specified index is negative
since:
JDK1.0 |
| set | | public void set(int bitIndex, boolean value)(Code) | | Sets the bit at the specified index to the specified value.
Parameters:
bitIndex - a bit index
Parameters:
value - a boolean value to set
throws:
IndexOutOfBoundsException - if the specified index is negative
since:
1.4 |
| set | | public void set(int fromIndex, int toIndex)(Code) | | Sets the bits from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to
true .
Parameters:
fromIndex - index of the first bit to be set
Parameters:
toIndex - index after the last bit to be set
throws:
IndexOutOfBoundsException - if fromIndex is negative,or toIndex is negative, or fromIndex islarger than toIndex
since:
1.4 |
| set | | public void set(int fromIndex, int toIndex, boolean value)(Code) | | Sets the bits from the specified
fromIndex (inclusive) to the
specified
toIndex (exclusive) to the specified value.
Parameters:
fromIndex - index of the first bit to be set
Parameters:
toIndex - index after the last bit to be set
Parameters:
value - value to set the selected bits to
throws:
IndexOutOfBoundsException - if fromIndex is negative,or toIndex is negative, or fromIndex islarger than toIndex
since:
1.4 |
| size | | public int size()(Code) | | Returns the number of bits of space actually in use by this
BitSet to represent bit values.
The maximum element in the set is the size - 1st element.
the number of bits currently in this bit set |
| toByteArray | | public byte[] toByteArray()(Code) | | Returns a new byte array containing all the bits in this bit set.
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 .
a byte array containing a little-endian representationof all the bits in this bit set
since:
1.7 |
| toLongArray | | public long[] toLongArray()(Code) | | Returns a new long array containing all the bits in this bit set.
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 .
a long array containing a little-endian representationof all the bits in this bit set
since:
1.7 |
| valueOf | | public static BitSet valueOf(long[] longs)(Code) | | Returns a new bit set containing all the bits in the given long array.
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)) .
Parameters:
longs - a long array containing a little-endian representationof a sequence of bits to be used as the initial bits of thenew bit set
since:
1.7 |
| valueOf | | public static BitSet valueOf(LongBuffer lb)(Code) | | Returns a new bit set containing all the bits in the given long
buffer between its position and limit.
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.
Parameters:
lb - a long buffer containing a little-endian representationof a sequence of bits between its position and limit, to beused as the initial bits of the new bit set
since:
1.7 |
| valueOf | | public static BitSet valueOf(byte[] bytes)(Code) | | Returns a new bit set containing all the bits in the given byte array.
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)) .
Parameters:
bytes - a byte array containing a little-endianrepresentation of a sequence of bits to be used as theinitial bits of the new bit set
since:
1.7 |
| valueOf | | public static BitSet valueOf(ByteBuffer bb)(Code) | | Returns a new bit set containing all the bits in the given byte
buffer between its position and limit.
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.
Parameters:
bb - a byte buffer containing a little-endian representationof a sequence of bits between its position and limit, to beused as the initial bits of the new bit set
since:
1.7 |
| xor | | public void xor(BitSet set)(Code) | | Performs a logical XOR of this bit set with the bit set
argument. This bit set is modified so that a bit in it has the
value
true if and only if one of the following
statements holds:
- The bit initially has the value
true , and the
corresponding bit in the argument has the value
false .
- The bit initially has the value
false , and the
corresponding bit in the argument has the value
true .
Parameters:
set - a bit set |
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