java.util
Class BitSet

java.lang.Object sample code for java.lang.Object definition code for java.lang.Object 
  extended by java.util.BitSet
All Implemented Interfaces:
Serializable sample code for java.io.Serializable definition code for java.io.Serializable , Cloneable sample code for java.lang.Cloneable definition code for java.lang.Cloneable

public class BitSet
extends Object sample code for java.lang.Object definition code for java.lang.Object
implements Cloneable sample code for java.lang.Cloneable definition code for java.lang.Cloneable , Serializable sample code for java.io.Serializable definition code for java.io.Serializable

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.

Since:
JDK1.0
See Also:
Serialized Form

Constructor Summary
BitSet sample code for java.util.BitSet.BitSet() definition code for java.util.BitSet.BitSet() ()
          Creates a new bit set.
BitSet sample code for java.util.BitSet.BitSet(int) definition code for java.util.BitSet.BitSet(int) (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
 void and sample code for java.util.BitSet.and(java.util.BitSet) definition code for java.util.BitSet.and(java.util.BitSet) (BitSet sample code for java.util.BitSet definition code for java.util.BitSet  set)
          Performs a logical AND of this target bit set with the argument bit set.
 void andNot sample code for java.util.BitSet.andNot(java.util.BitSet) definition code for java.util.BitSet.andNot(java.util.BitSet) (BitSet sample code for java.util.BitSet definition code for java.util.BitSet  set)
          Clears all of the bits in this BitSet whose corresponding bit is set in the specified BitSet.
 int cardinality sample code for java.util.BitSet.cardinality() definition code for java.util.BitSet.cardinality() ()
          Returns the number of bits set to true in this BitSet.
 void clear sample code for java.util.BitSet.clear() definition code for java.util.BitSet.clear() ()
          Sets all of the bits in this BitSet to false.
 void clear sample code for java.util.BitSet.clear(int) definition code for java.util.BitSet.clear(int) (int bitIndex)
          Sets the bit specified by the index to false.
 void clear sample code for java.util.BitSet.clear(int, int) definition code for java.util.BitSet.clear(int, int) (int fromIndex, int toIndex)
          Sets the bits from the specified fromIndex(inclusive) to the specified toIndex(exclusive) to false.
 Object sample code for java.lang.Object definition code for java.lang.Object clone sample code for java.util.BitSet.clone() definition code for java.util.BitSet.clone() ()
          Cloning this BitSet produces a new BitSet that is equal to it.
 boolean equals sample code for java.util.BitSet.equals(java.lang.Object) definition code for java.util.BitSet.equals(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  obj)
          Compares this object against the specified object.
 void flip sample code for java.util.BitSet.flip(int) definition code for java.util.BitSet.flip(int) (int bitIndex)
          Sets the bit at the specified index to the complement of its current value.
 void flip sample code for java.util.BitSet.flip(int, int) definition code for java.util.BitSet.flip(int, int) (int fromIndex, int toIndex)
          Sets each bit from the specified fromIndex(inclusive) to the specified toIndex(exclusive) to the complement of its current value.
 boolean get sample code for java.util.BitSet.get(int) definition code for java.util.BitSet.get(int) (int bitIndex)
          Returns the value of the bit with the specified index.
 BitSet sample code for java.util.BitSet definition code for java.util.BitSet get sample code for java.util.BitSet.get(int, int) definition code for java.util.BitSet.get(int, int) (int fromIndex, int toIndex)
          Returns a new BitSet composed of bits from this BitSet from fromIndex(inclusive) to toIndex(exclusive).
 int hashCode sample code for java.util.BitSet.hashCode() definition code for java.util.BitSet.hashCode() ()
          Returns a hash code value for this bit set.
 boolean intersects sample code for java.util.BitSet.intersects(java.util.BitSet) definition code for java.util.BitSet.intersects(java.util.BitSet) (BitSet sample code for java.util.BitSet definition code for java.util.BitSet  set)
          Returns true if the specified BitSet has any bits set to true that are also set to true in this BitSet.
 boolean isEmpty sample code for java.util.BitSet.isEmpty() definition code for java.util.BitSet.isEmpty() ()
          Returns true if this BitSet contains no bits that are set to true.
 int length sample code for java.util.BitSet.length() definition code for java.util.BitSet.length() ()
          Returns the "logical size" of this BitSet: the index of the highest set bit in the BitSet plus one.
 int nextClearBit sample code for java.util.BitSet.nextClearBit(int) definition code for java.util.BitSet.nextClearBit(int) (int fromIndex)
          Returns the index of the first bit that is set to false that occurs on or after the specified starting index.
 int nextSetBit sample code for java.util.BitSet.nextSetBit(int) definition code for java.util.BitSet.nextSetBit(int) (int fromIndex)
          Returns the index of the first bit that is set to true that occurs on or after the specified starting index.
 void or sample code for java.util.BitSet.or(java.util.BitSet) definition code for java.util.BitSet.or(java.util.BitSet) (BitSet sample code for java.util.BitSet definition code for java.util.BitSet  set)
          Performs a logical OR of this bit set with the bit set argument.
 void set sample code for java.util.BitSet.set(int) definition code for java.util.BitSet.set(int) (int bitIndex)
          Sets the bit at the specified index to true.
 void set sample code for java.util.BitSet.set(int, boolean) definition code for java.util.BitSet.set(int, boolean) (int bitIndex, boolean value)
          Sets the bit at the specified index to the specified value.
 void set sample code for java.util.BitSet.set(int, int) definition code for java.util.BitSet.set(int, int) (int fromIndex, int toIndex)
          Sets the bits from the specified fromIndex(inclusive) to the specified toIndex(exclusive) to true.
 void set sample code for java.util.BitSet.set(int, int, boolean) definition code for java.util.BitSet.set(int, int, boolean) (int fromIndex, int toIndex, boolean value)
          Sets the bits from the specified fromIndex(inclusive) to the specified toIndex(exclusive) to the specified value.
 int size sample code for java.util.BitSet.size() definition code for java.util.BitSet.size() ()
          Returns the number of bits of space actually in use by this BitSet to represent bit values.
 String sample code for java.lang.String definition code for java.lang.String toString sample code for java.util.BitSet.toString() definition code for java.util.BitSet.toString() ()
          Returns a string representation of this bit set.
 void xor sample code for java.util.BitSet.xor(java.util.BitSet) definition code for java.util.BitSet.xor(java.util.BitSet) (BitSet sample code for java.util.BitSet definition code for java.util.BitSet  set)
          Performs a logical XOR of this bit set with the bit set argument.
 
Methods inherited from class java.lang.Object sample code for java.lang.Object definition code for java.lang.Object
finalize sample code for java.lang.Object.finalize() definition code for java.lang.Object.finalize() , getClass sample code for java.lang.Object.getClass() definition code for java.lang.Object.getClass() , notify sample code for java.lang.Object.notify() definition code for java.lang.Object.notify() , notifyAll sample code for java.lang.Object.notifyAll() definition code for java.lang.Object.notifyAll() , wait sample code for java.lang.Object.wait() definition code for java.lang.Object.wait() , wait sample code for java.lang.Object.wait(long) definition code for java.lang.Object.wait(long) , wait sample code for java.lang.Object.wait(long, int) definition code for java.lang.Object.wait(long, int)
 

Constructor Detail

BitSet sample code for java.util.BitSet() definition code for java.util.BitSet()

public BitSet()
Creates a new bit set. All bits are initially false.


BitSet sample code for java.util.BitSet(int) definition code for java.util.BitSet(int)

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. All bits are initially false.

Parameters:
nbits - the initial size of the bit set.
Throws:
NegativeArraySizeException sample code for java.lang.NegativeArraySizeException definition code for java.lang.NegativeArraySizeException - if the specified initial size is negative.
Method Detail

flip sample code for java.util.BitSet.flip(int) definition code for java.util.BitSet.flip(int)

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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.
Since:
1.4

flip sample code for java.util.BitSet.flip(int, int) definition code for java.util.BitSet.flip(int, int)

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.

Parameters:
fromIndex - index of the first bit to flip.
toIndex - index after the last bit to flip.
Throws:
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex.
Since:
1.4

set sample code for java.util.BitSet.set(int) definition code for java.util.BitSet.set(int)

public void set(int bitIndex)
Sets the bit at the specified index to true.

Parameters:
bitIndex - a bit index.
Throws:
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.
Since:
JDK1.0

set sample code for java.util.BitSet.set(int, boolean) definition code for java.util.BitSet.set(int, boolean)

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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.
Since:
1.4

set sample code for java.util.BitSet.set(int, int) definition code for java.util.BitSet.set(int, int)

public void set(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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex.
Since:
1.4

set sample code for java.util.BitSet.set(int, int, boolean) definition code for java.util.BitSet.set(int, int, boolean)

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.

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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex.
Since:
1.4

clear sample code for java.util.BitSet.clear(int) definition code for java.util.BitSet.clear(int)

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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.
Since:
JDK1.0

clear sample code for java.util.BitSet.clear(int, int) definition code for java.util.BitSet.clear(int, int)

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.
toIndex - index after the last bit to be cleared.
Throws:
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex.
Since:
1.4

clear sample code for java.util.BitSet.clear() definition code for java.util.BitSet.clear()

public void clear()
Sets all of the bits in this BitSet to false.

Since:
1.4

get sample code for java.util.BitSet.get(int) definition code for java.util.BitSet.get(int)

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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.

get sample code for java.util.BitSet.get(int, int) definition code for java.util.BitSet.get(int, int)

public BitSet sample code for java.util.BitSet definition code for java.util.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.
toIndex - index after the last bit to include.
Returns:
a new BitSet from a range of this BitSet.
Throws:
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if fromIndex is negative, or toIndex is negative, or fromIndex is larger than toIndex.
Since:
1.4

nextSetBit sample code for java.util.BitSet.nextSetBit(int) definition code for java.util.BitSet.nextSetBit(int)

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: 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).
Returns:
the index of the next set bit.
Throws:
IndexOutOfBoundsException sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.
Since:
1.4

nextClearBit sample code for java.util.BitSet.nextClearBit(int) definition code for java.util.BitSet.nextClearBit(int)

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 sample code for java.lang.IndexOutOfBoundsException definition code for java.lang.IndexOutOfBoundsException - if the specified index is negative.
Since:
1.4

length sample code for java.util.BitSet.length() definition code for java.util.BitSet.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 sample code for java.util.BitSet.isEmpty() definition code for java.util.BitSet.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 sample code for java.util.BitSet.intersects(java.util.BitSet) definition code for java.util.BitSet.intersects(java.util.BitSet)

public boolean intersects(BitSet sample code for java.util.BitSet definition code for java.util.BitSet  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 sample code for java.util.BitSet.cardinality() definition code for java.util.BitSet.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 sample code for java.util.BitSet.and(java.util.BitSet) definition code for java.util.BitSet.and(java.util.BitSet)

public void and(BitSet sample code for java.util.BitSet definition code for java.util.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 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 sample code for java.util.BitSet.or(java.util.BitSet) definition code for java.util.BitSet.or(java.util.BitSet)

public void or(BitSet sample code for java.util.BitSet definition code for java.util.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 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 sample code for java.util.BitSet.xor(java.util.BitSet) definition code for java.util.BitSet.xor(java.util.BitSet)

public void xor(BitSet sample code for java.util.BitSet definition code for java.util.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 true if and only if one of the following statements holds:

Parameters:
set - a bit set.

andNot sample code for java.util.BitSet.andNot(java.util.BitSet) definition code for java.util.BitSet.andNot(java.util.BitSet)

public void andNot(BitSet sample code for java.util.BitSet definition code for java.util.BitSet  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:
JDK1.2

hashCode sample code for java.util.BitSet.hashCode() definition code for java.util.BitSet.hashCode()

public int hashCode()
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.

Overrides:
hashCode sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a hash code value for this bit set.
See Also:
Object.equals(java.lang.Object) sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , Hashtable sample code for java.util.Hashtable definition code for java.util.Hashtable

size sample code for java.util.BitSet.size() definition code for java.util.BitSet.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 sample code for java.util.BitSet.equals(java.lang.Object) definition code for java.util.BitSet.equals(java.lang.Object)

public boolean equals(Object sample code for java.lang.Object definition code for java.lang.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 the equals method of Object.

Overrides:
equals sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) in class Object sample code for java.lang.Object definition code for java.lang.Object
Parameters:
obj - the object to compare with.
Returns:
true if the objects are the same; false otherwise.
See Also:
size() sample code for java.util.BitSet.size() definition code for java.util.BitSet.size()

clone sample code for java.util.BitSet.clone() definition code for java.util.BitSet.clone()

public Object sample code for java.lang.Object definition code for java.lang.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.

Overrides the clone method of Object.

Overrides:
clone sample code for java.lang.Object.clone() definition code for java.lang.Object.clone() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a clone of this bit set.
See Also:
size() sample code for java.util.BitSet.size() definition code for java.util.BitSet.size()

toString sample code for java.util.BitSet.toString() definition code for java.util.BitSet.toString()

public String sample code for java.lang.String definition code for java.lang.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.

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}".

Overrides:
toString sample code for java.lang.Object.toString() definition code for java.lang.Object.toString() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a string representation of this bit set.