Class BS

Method Details

• newN

  public static BS newN(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. All bits are initially false.

  Parameters:

  nbits - the initial size of the bit set

  Returns:

  bs

  Throws:

  NegativeArraySizeException - if the specified initial size is negative

• 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:

  JDK1.0

• setBitTo

  public void setBitTo(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

• setBits

  public void setBits(int fromIndex, int toIndex)

  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

  toIndex - index after the last bit to be set

  Throws:

  IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

  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:

  JDK1.0

• clearBits

  public void clearBits(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

  toIndex - index after the last bit to be cleared

  Throws:

  IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex

  Since:

  1.4

• clearAll

  public void clearAll()

  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 true if the bit with the index bitIndex is currently set in this BitSet; otherwise, the result is false.

  Parameters:

  bitIndex - the bit index

  Returns:

  the value of the bit with the specified index

  Throws:

  IndexOutOfBoundsException - if the specified index is negative

• nextSetBit

  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. If no such bit exists then -1 is returned.

  To iterate over the true bits in a BitSet, use the following loop:

• nextClearBit

  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)

  Returns:

  the index of the next clear bit

  Throws:

  IndexOutOfBoundsException - if the specified index is negative

  Since:

  1.4

• length

  public int length()

  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.

  Returns:

  the logical size of this BitSet

  Since:

  1.2

• isEmpty

  public boolean isEmpty()

  Returns true if this BitSet contains no bits that are set to true.

  Returns:

  boolean indicating whether this BitSet is empty

  Since:

  1.4

• intersects

  public boolean intersects(BS set)

  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

  Returns:

  boolean indicating whether this BitSet intersects the specified BitSet

  Since:

  1.4

• cardinality

  public int cardinality()

  Returns the number of bits set to true in this BitSet.

  Returns:

  the number of bits set to true in this BitSet

  Since:

  1.4

• and

  public void and(BS 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 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

• or

  public void or(BS 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 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

• xor

  public void xor(BS 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 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

• andNot

  public void andNot(BS set)

  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

• hashCode

  public int hashCode()

  Returns a hash code value for this bit set. The hash 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, words, 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) < words.length) && ((words[k >> 6] & (1 << (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 = words.length; --i >= 0;) {
     h ˆ= words[i] * (i + 1);
   }
   return (int) ((h >> 32) ˆ h);
  }
  

  Note that the hash code values change if the set of bits is altered.

  Overrides the hashCode method of Object.

  Overrides:

  hashCode in class Object

  Returns:

  a hash code value for this bit set.

• size

  public int size()

  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.

  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 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:

  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 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.

  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 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.

  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}".

  Overrides:

  toString in class Object

  Returns:

  a string representation of this bit set

• copy

  public static BS copy(BS bitsetToCopy)

  fast copy

  Parameters:

  bitsetToCopy -

  Returns:

  bs

• cardinalityN

  public int cardinalityN(int max)

  Parameters:

  max -

  Returns:

  n bits below max

• toJSON

  public String toJSON()

  Specified by:

  toJSON in interface JSONEncodable

• escape

  public static String escape(BS bs, char chOpen, char chClose)

• unescape

  public static BS unescape(String str)