| 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
version:
1.46, 02/02/00
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.
Parameters:
fromIndex - index of the first bit to be cleared.
Parameters:
toIndex - index after the last bit to be cleared. | | 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.
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. | | 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 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).
Parameters:
fromIndex - index of the first bit to include.
Parameters:
toIndex - index after the last bit to include. | | public int | hashCode()
Returns a hash code value for this bit set. | | 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.
Parameters:
fromIndex - the index to start checking from (inclusive). | | 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 String | toString()
Returns a string representation of this bit set. | | 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.
exception:
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 thisBitSet.
since:
JDK1.2 |
| cardinality | | public int cardinality()(Code) | | Returns the number of bits set to true in this
BitSet.
the number of bits set to true in thisBitSet.
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.
exception:
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.
exception:
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 and the same
current size.
Overrides the clone method of Object.
a clone of this bit set.
See Also: java.util.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.
Overrides the equals method of Object.
Parameters:
obj - the object to compare with. true if the objects are the same;false otherwise.
See Also: java.util.BitSet.size |
| flip | | public void flip(int bitIndex)(Code) | | Sets the bit at the specified index to to the complement of its
current value.
Parameters:
bitIndex - the index of the bit to flip.
exception:
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.
exception:
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.
exception:
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.
exception:
IndexOutOfBoundsException - if fromIndex is negative,or toIndex is negative, or fromIndex islarger than toIndex.
since:
1.4 |
| hashCode | | public int hashCode()(Code) | | Returns a hash code value for this bit set. The has code
depends only on which bits have been set within this
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 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.
a hash code value for this bit set. |
| 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.
exception:
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.
exception:
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.
exception:
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
exception:
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. |
| toString | | public String toString()(Code) | | Returns a string representation of this bit set. For every index
for which this 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.
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}".
a string representation of this bit set. |
| 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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