Constructor Summary

Method Summary

Constructor Details

• BitSet

  public BitSet()

  Creates a new bit set. All bits are initiallyfalse.

• BitSet

  public BitSet(int nbits)

  Creates a bit set whose initial size is large enough to explicitly represent bits with indices in the range0 throughnbits-1. All bits are initiallyfalse.

  Parameters:

  nbits - the initial size of the bit set

  Throws:

  NegativeArraySizeException - if the specified initial size is negative

Method Details

• 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 toBitSet.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:

  aBitSet containing 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:

  aBitSet containing 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 toBitSet.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:

  aBitSet containing 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:

  aBitSet containing 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)/8 and
  s.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)/64 and
  s.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 specifiedfromIndex (inclusive) to the specifiedtoIndex (exclusive) to the complement of its current value.

  Parameters:

  fromIndex - index of the first bit to flip

  toIndex - index after the last bit to flip

  Throws:

  IndexOutOfBoundsException - iffromIndex is negative, ortoIndex is negative, orfromIndex is larger thantoIndex

  Since:

  1.4

• set

  public void set(int bitIndex)

  Sets the bit at the specified index totrue.

  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 index

  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)

  Sets the bits from the specifiedfromIndex (inclusive) to the specifiedtoIndex (exclusive) totrue.

  Parameters:

  fromIndex - index of the first bit to be set

  toIndex - index after the last bit to be set

  Throws:

  IndexOutOfBoundsException - iffromIndex is negative, ortoIndex is negative, orfromIndex is larger thantoIndex

  Since:

  1.4

• set

  public void set(int fromIndex, int toIndex, boolean value)

  Sets the bits from the specifiedfromIndex (inclusive) to the specifiedtoIndex (exclusive) to the specified value.

  Parameters:

  fromIndex - index of the first bit to be set

  toIndex - index after the last bit to be set

  value - value to set the selected bits to

  Throws:

  IndexOutOfBoundsException - iffromIndex is negative, ortoIndex is negative, orfromIndex is larger thantoIndex

  Since:

  1.4

• clear

  public void clear(int bitIndex)

  Sets the bit specified by the index tofalse.

  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 specifiedfromIndex (inclusive) to the specifiedtoIndex (exclusive) tofalse.

  Parameters:

  fromIndex - index of the first bit to be cleared

  toIndex - index after the last bit to be cleared

  Throws:

  IndexOutOfBoundsException - iffromIndex is negative, ortoIndex is negative, orfromIndex is larger thantoIndex

  Since:

  1.4

• clear

  public void clear()

  Sets all of the bits in this BitSet tofalse.

  Since:

  1.4

• get

  public boolean get(int bitIndex)

  Returns the value of the bit with the specified index. The value istrue if the bit with the indexbitIndex is 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 newBitSet composed of bits from thisBitSet fromfromIndex (inclusive) totoIndex (exclusive).

  Parameters:

  fromIndex - index of the first bit to include

  toIndex - index after the last bit to include

  Returns:

  a newBitSet from a range of thisBitSet

  Throws:

  IndexOutOfBoundsException - iffromIndex is negative, ortoIndex is negative, orfromIndex is larger thantoIndex

  Since:

  1.4

• nextSetBit

  public int nextSetBit(int fromIndex)

  Returns the index of the first bit that is set totrue that occurs on or after the specified starting index. If no such bit exists then-1 is returned.

  To iterate over thetrue bits 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-1 if 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 tofalse that 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 totrue 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 thetrue bits 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-1 if 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 tofalse 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.

  Parameters:

  fromIndex - the index to start checking from (inclusive)

  Returns:

  the index of the previous clear bit, or-1 if 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 thisBitSet: the index of the highest set bit in theBitSet plus one. Returns zero if theBitSet contains no set bits.

  Returns:

  the logical size of thisBitSet

  Since:

  1.2

• isEmpty

  public boolean isEmpty()

  Returns true if thisBitSet contains no bits that are set totrue.

  Returns:

  boolean indicating whether thisBitSet is empty

  Since:

  1.4

• intersects

  public boolean intersects(BitSet set)

  Returns true if the specifiedBitSet has any bits set totrue that are also set totrue in thisBitSet.

  Parameters:

  set -BitSet to intersect with

  Returns:

  boolean indicating whether thisBitSet intersects the specifiedBitSet

  Since:

  1.4

• cardinality

  public int cardinality()

  Returns the number of bits set totrue in thisBitSet.

  Returns:

  the number of bits set totrue in thisBitSet

  Since:

  1.4

• and

  public void and(BitSet set)

  Performs a logicalAND of this target bit set with the argument bit set. This bit set is modified so that each bit in it has the valuetrue if and only if it both initially had the valuetrue and 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 logicalOR of this bit set with the bit set argument. This bit set is modified so that a bit in it has the valuetrue if and only if it either already had the valuetrue or the corresponding bit in the bit set argument has the valuetrue.

  Parameters:

  set - a bit set

• xor

  public void xor(BitSet set)

  Performs a logicalXOR of this bit set with the bit set argument. This bit set is modified so that a bit in it has the valuetrue if and only if one of the following statements holds:

  • The bit initially has the valuetrue, and the corresponding bit in the argument has the valuefalse.
  • The bit initially has the valuefalse, and the corresponding bit in the argument has the valuetrue.

  Parameters:

  set - a bit set

• andNot

  public void andNot(BitSet set)

  Clears all of the bits in thisBitSet whose corresponding bit is set in the specifiedBitSet.

  Parameters:

  set - theBitSet with 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 thisBitSet.

  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:

  hashCode in class Object

  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 thisBitSet to 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 bit set against the specified object. The result istrue if and only if the argument is notnull and is aBitSet object that has exactly the same set of bits set totrue as this bit set. That is, for every nonnegativeint indexk,

  ((BitSet)obj).get(k) == this.get(k)

  must be true. The current sizes of the two bit sets are not compared.

  Overrides:

  equals in class Object

  Parameters:

  obj - the object to compare with

  Returns:

  true if the objects are the same;false otherwise

  See Also:

  • size()

• clone

  public Object clone()

  Cloning thisBitSet produces a newBitSet that is equal to it. The clone of the bit set is another bit set that has exactly the same bits set totrue as this bit set.

  Overrides:

  clone in class Object

  Returns:

  a clone of this bit set

  See Also:

  • size()

• toString

  public String toString()

  Returns a string representation of this bit set. For every index for which thisBitSet 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();

  NowdrPepper.toString() returns "{}".

   drPepper.set(2);

  NowdrPepper.toString() returns "{2}".

   drPepper.set(4); drPepper.set(10);

  NowdrPepper.toString() returns "{2, 4, 10}".

  Overrides:

  toString in class Object

  Returns:

  a string representation of this bit set

• stream

  public IntStream stream()

  Returns a stream of indices for which thisBitSet 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 thecardinality() method.

  The stream binds to this bit set when the terminal stream operation commences (specifically, the spliterator for the stream islate-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