BitSet (Java SE 10 & JDK 10 )
-
-
Constructor Detail
-
BitSet
public BitSet()
Creates a new bit set. All bits are initially
false.
-
BitSet
public BitSet(int nbits)
Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range
0throughnbits-1. All bits are initiallyfalse.- Parameters:
nbits- the initial size of the bit set- Throws:
NegativeArraySizeException- if the specified initial size is negative
-
-
Method Detail
-
valueOf
public static BitSet valueOf(long[] longs)
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 alln < 64 * longs.length.This method is equivalent to
BitSet.valueOf(LongBuffer.wrap(longs)).- Parameters:
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 set- Returns:
- a
BitSetcontaining all the bits in the long array - Since:
- 1.7
-
valueOf
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.
More precisely,
BitSet.valueOf(lb).get(n) == ((lb.get(lb.position()+n/64) & (1L<<(n%64))) != 0)
for alln < 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 representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit set- Returns:
- a
BitSetcontaining all the bits in the buffer in the specified range - Since:
- 1.7
-
valueOf
public static BitSet valueOf(byte[] bytes)
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 alln < 8 * bytes.length.This method is equivalent to
BitSet.valueOf(ByteBuffer.wrap(bytes)).- Parameters:
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 set- Returns:
- a
BitSetcontaining all the bits in the byte array - Since:
- 1.7
-
valueOf
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.
More precisely,
BitSet.valueOf(bb).get(n) == ((bb.get(bb.position()+n/8) & (1<<(n%8))) != 0)
for alln < 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 representation of a sequence of bits between its position and limit, to be used as the initial bits of the new bit set- Returns:
- a
BitSetcontaining all the bits in the buffer in the specified range - Since:
- 1.7
-
toByteArray
public byte[] toByteArray()
Returns a new byte array containing all the bits in this bit set.
More precisely, if
byte[] bytes = s.toByteArray();
thenbytes.length == (s.length()+7)/8ands.get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)
for alln < 8 * bytes.length.- Returns:
- a byte array containing a little-endian representation of all the bits in this bit set
- Since:
- 1.7
-
toLongArray
public long[] toLongArray()
Returns a new long array containing all the bits in this bit set.
More precisely, if
long[] longs = s.toLongArray();
thenlongs.length == (s.length()+63)/64ands.get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)
for alln < 64 * longs.length.- Returns:
- a long array containing a little-endian representation of all the bits in this bit set
- Since:
- 1.7
-
flip
public void flip(int bitIndex)
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)Sets each bit from the specified
fromIndex(inclusive) to the specifiedtoIndex(exclusive) to the complement of its current value.- Parameters:
fromIndex- index of the first bit to fliptoIndex- index after the last bit to flip- Throws:
IndexOutOfBoundsException- iffromIndexis negative, ortoIndexis negative, orfromIndexis larger thantoIndex- Since:
- 1.4
-
set
public void set(int bitIndex)
Sets the bit at the specified index to
true.- Parameters:
bitIndex- a bit index- Throws:
IndexOutOfBoundsException- if the specified index is negative- Since:
- 1.0
-
set
public void set(int bitIndex, boolean value)Sets the bit at the specified index to the specified value.
- Parameters:
bitIndex- a bit indexvalue- a boolean value to set- Throws:
IndexOutOfBoundsException- if the specified index is negative- Since:
- 1.4
-
set
public void set(int fromIndex, int toIndex)Sets the bits from the specified
fromIndex(inclusive) to the specifiedtoIndex(exclusive) totrue.- Parameters:
fromIndex- index of the first bit to be settoIndex- index after the last bit to be set- Throws:
IndexOutOfBoundsException- iffromIndexis negative, ortoIndexis negative, orfromIndexis larger thantoIndex- Since:
- 1.4
-
set
public void set(int fromIndex, int toIndex, boolean value)Sets the bits from the specified
fromIndex(inclusive) to the specifiedtoIndex(exclusive) to the specified value.- Parameters:
fromIndex- index of the first bit to be settoIndex- index after the last bit to be setvalue- value to set the selected bits to- Throws:
IndexOutOfBoundsException- iffromIndexis negative, ortoIndexis negative, orfromIndexis larger thantoIndex- Since:
- 1.4
-
clear
public void clear(int bitIndex)
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:
- 1.0
-
clear
public void clear(int fromIndex, int toIndex)Sets the bits from the specified
fromIndex(inclusive) to the specifiedtoIndex(exclusive) tofalse.- Parameters:
fromIndex- index of the first bit to be clearedtoIndex- index after the last bit to be cleared- Throws:
IndexOutOfBoundsException- iffromIndexis negative, ortoIndexis negative, orfromIndexis larger thantoIndex- Since:
- 1.4
-
clear
public void clear()
Sets all of the bits in this BitSet to
false.- Since:
- 1.4
-
get
public boolean get(int bitIndex)
Returns the value of the bit with the specified index. The value is
trueif the bit with the indexbitIndexis currently set in thisBitSet; otherwise, the result isfalse.- Parameters:
bitIndex- the bit index- Returns:
- 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)
Returns a new
BitSetcomposed of bits from thisBitSetfromfromIndex(inclusive) totoIndex(exclusive).- Parameters:
fromIndex- index of the first bit to includetoIndex- index after the last bit to include- Returns:
- a new
BitSetfrom a range of thisBitSet - Throws:
IndexOutOfBoundsException- iffromIndexis negative, ortoIndexis negative, orfromIndexis larger thantoIndex- Since:
- 1.4
-
nextSetBit
public int nextSetBit(int fromIndex)
Returns the index of the first bit that is set to
truethat occurs on or after the specified starting index. If no such bit exists then-1is returned.To iterate over the
truebits in aBitSet, 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 } }- Parameters:
fromIndex- the index to start checking from (inclusive)- Returns:
- the index of the next set bit, or
-1if there is no such bit - Throws:
IndexOutOfBoundsException- if the specified index is negative- Since:
- 1.4
-
nextClearBit
public int nextClearBit(int fromIndex)
Returns the index of the first bit that is set to
falsethat occurs on or after the specified starting index.- Parameters:
fromIndex- the index to start checking from (inclusive)- Returns:
- the index of the next clear bit
- Throws:
IndexOutOfBoundsException- if the specified index is negative- Since:
- 1.4
-
previousSetBit
public int previousSetBit(int fromIndex)
Returns the index of the nearest bit that is set to
truethat occurs on or before the specified starting index. If no such bit exists, or if-1is given as the starting index, then-1is returned.To iterate over the
truebits in aBitSet, use the following loop:for (int i = bs.length(); (i = bs.previousSetBit(i-1)) >= 0; ) { // operate on index i here }- Parameters:
fromIndex- the index to start checking from (inclusive)- Returns:
- the index of the previous set bit, or
-1if there is no such bit - Throws:
IndexOutOfBoundsException- if the specified index is less than-1- Since:
- 1.7
-
previousClearBit
public int previousClearBit(int fromIndex)
Returns the index of the nearest bit that is set to
falsethat occurs on or before the specified starting index. If no such bit exists, or if-1is given as the starting index, then-1is returned.- Parameters:
fromIndex- the index to start checking from (inclusive)- Returns:
- the index of the previous clear bit, or
-1if there is no such bit - Throws:
IndexOutOfBoundsException- if the specified index is less than-1- Since:
- 1.7
-
length
public int length()
Returns the "logical size" of this
BitSet: the index of the highest set bit in theBitSetplus one. Returns zero if theBitSetcontains no set bits.- Returns:
- the logical size of this
BitSet - Since:
- 1.2
-
isEmpty
public boolean isEmpty()
Returns true if this
BitSetcontains no bits that are set totrue.- Returns:
- boolean indicating whether this
BitSetis empty - Since:
- 1.4
-
intersects
public boolean intersects(BitSet set)
Returns true if the specified
BitSethas any bits set totruethat are also set totruein thisBitSet.- Parameters:
set-BitSetto intersect with- Returns:
- boolean indicating whether this
BitSetintersects the specifiedBitSet - Since:
- 1.4
-
cardinality
public int cardinality()
Returns the number of bits set to
truein thisBitSet.- Returns:
- the number of bits set to
truein thisBitSet - Since:
- 1.4
-
and
public void and(BitSet set)
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
trueif and only if it both initially had the valuetrueand the corresponding bit in the bit set argument also had the valuetrue.- Parameters:
set- a bit set
-
or
public void or(BitSet set)
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
trueif and only if it either already had the valuetrueor the corresponding bit in the bit set argument has the valuetrue.- Parameters:
set- a bit set
-
xor
public void xor(BitSet set)
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
trueif 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 valuefalse. - The bit initially has the value
false, and the corresponding bit in the argument has the valuetrue.
- Parameters:
set- a bit set
- The bit initially has the value
-
andNot
public void andNot(BitSet set)
Clears all of the bits in this
BitSetwhose corresponding bit is set in the specifiedBitSet.- Parameters:
set- theBitSetwith which to mask thisBitSet- Since:
- 1.2
-
hashCode
public int hashCode()
Returns the hash code value for this bit set. The hash code depends only on which bits are set within this
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.
- Overrides:
hashCodein classObject- Returns:
- the hash code value for this bit set
- See Also:
Object.equals(java.lang.Object),System.identityHashCode(java.lang.Object)
-
size
public int size()
Returns the number of bits of space actually in use by this
BitSetto represent bit values. The maximum element in the set is the size - 1st element.- Returns:
- the number of bits currently in this bit set
-
equals
public boolean equals(Object obj)
Compares this object against the specified object. The result is
trueif and only if the argument is notnulland is aBitsetobject that has exactly the same set of bits set totrueas this bit set. That is, for every nonnegativeintindexk,((BitSet)obj).get(k) == this.get(k)
must be true. The current sizes of the two bit sets are not compared.
-
clone
public Object clone()
Cloning this
BitSetproduces a newBitSetthat is equal to it. The clone of the bit set is another bit set that has exactly the same bits set totrueas this bit set.
-
toString
public String toString()
Returns a string representation of this bit set. For every index for which this
BitSetcontains 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}".
-
stream
public IntStream stream()
Returns a stream of indices for which this
BitSetcontains 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 thecardinality()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.
- Returns:
- a stream of integers representing set indices
- Since:
- 1.8
-
-