Class SparseBitSet

java.lang.Object
com.zaxxer.sparsebits.SparseBitSet
All Implemented Interfaces:
Serializable, Cloneable

public class SparseBitSet extends Object implements Cloneable, Serializable
This class implements a set of bits that grows as needed. Each bit of the bit set represents a boolean value. The values of a SparseBitSet are indexed by non-negative integers. Individual indexed values may be examined, set, cleared, or modified by logical operations. One SparseBitSet or logical value may be used to modify the contents of (another) SparseBitSet through logical AND, logical inclusive OR, logical exclusive OR, and And NOT operations over all or part of the bit sets.

All values in a bit set initially have the value false.

Every bit set has a current size, which is the number of bits of space nominally in use by the bit set from the first set bit to just after the last set bit. The length of the bit set effectively tells the position available after the last bit of the SparseBitSet.

The maximum cardinality of a SparseBitSet is Integer.MAX_VALUE, which means the bits of a SparseBitSet are labelled 0 .. Integer.MAX_VALUE − 1. After the last set bit of a SparseBitSet, any attempt to find a subsequent bit (nextSetBit()), will return an value of −1. If an attempt is made to use nextClearBit(), and all the bits are set from the starting position of the search to the bit labelled Integer.MAX_VALUE − 1, then similarly −1 will be returned.

Unless otherwise noted, passing a null parameter to any of the methods in a SparseBitSet will result in a NullPointerException.

A SparseBitSet is not safe for multi-threaded use without external synchronization.

Since:
1.6
Version:
1.0, 2009-03-17
See Also:
  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    protected static class 
    This strategy class is used by the setScanner to carry out the a variety of operations on this set, and usually a second set.
    protected static class 
    AndNot of two sets.
    protected static class 
    And of two sets.
    protected class 
    This class holds the values related to various statistics kept about the bit set.
    protected static class 
    Clear clears bits in the a set.
    protected static class 
    Copies the needed parts of the b set to the a set.
    protected static class 
    Equals compares bits in the a set with those in the b set.
    protected static class 
    Flip inverts the bits of the a set within the given range.
    protected static class 
    Intersect has a true result if any word in the a set has a bit in common with the b set.
    protected static class 
    Or of two sets.
    protected static class 
    Set creates entries everywhere within the range.
    static enum 
    These enumeration values are used as labels for the values in the String created by the statistics() method.
    protected class 
    Update the seven statistics that are computed for each set.
    protected static class 
    The XOR of level3 blocks is computed.
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected static final SparseBitSet.AndNotStrategy
    Word and block andNot strategy.
    protected static final SparseBitSet.AndStrategy
    Word and block and strategy.
    protected long[][][]
    The storage for this SparseBitSet.
    protected int
    For the current size of the bits array, this is the maximum possible length of the bit set, i.e., the index of the last possible bit, plus one.
    Holds reference to the cache of statistics values computed by the UpdateStrategy
    protected static final SparseBitSet.ClearStrategy
    Word and block clear strategy.
    protected int
    This value controls for format of the toString() output.
    (package private) static int
    The compaction count default.
    protected static final SparseBitSet.CopyStrategy
    Word and block copy strategy.
    Word and block equals strategy.
    protected static final SparseBitSet.FlipStrategy
    Word and block flip strategy.
    protected static final int
    The number of bits in a positive integer, and the size of permitted index of a bit in the bit set.
    Word and block intersects strategy.
    protected static final int
    LENGTH2 is the number of entries in the any level2 area.
    protected static final int
    LENGTH2_SIZE is maximum index of a LEVEL2 page.
    protected static final int
    LENGTH3 is the number of entries in the any level3 block.
    protected static final int
    LENGTH3_SIZE is maximum index of a LEVEL3 page.
    protected static final int
    The number of bits in a long value.
    protected static final int
    LENGTH4_SIZE is maximum index of a bit in a LEVEL4 word.
    protected static final int
    LEVEL1 is the number of bits of the level1 address.
    protected static final int
    LEVEL2 is the number of bits of the level2 address.
    protected static final int
    LEVEL3 is the number of bits of the level3 address.
    protected static final int
    The label (index) of a bit in the bit set is essentially broken into 4 "levels".
    protected static final int
    MASK2 is the mask to extract the LEVEL2 address from a word index (after shifting by SHIFT3 and SHIFT2).
    protected static final int
    MASK3 is the mask to extract the LEVEL3 address from a word index (after shifting by SHIFT3).
    protected static final int
    MAX_LENGTH1 is the maximum number of entries in the level1 set array.
    protected static final SparseBitSet.OrStrategy
    Word and block or strategy.
    private static final long
    serialVersionUID
    protected static final SparseBitSet.SetStrategy
    Word and block set strategy.
    protected static final int
    SHIFT1 is the shift to bring the level1 address (from the word index) to the right end (i.e., after shifting by SHIFT3).
    protected static final int
    SHIFT2 is the shift to bring the level2 address (from the word index) to the right end (i.e., after shifting by SHIFT3).
    protected static final int
    The shift to create the word index.
    protected long[]
    A spare level 3 block is kept for use when scanning.
    protected static final int
    UNIT is the greatest number of bits that can be held in one level1 entry.
    Word and block update strategy.
    protected static final SparseBitSet.XorStrategy
    Word and block xor strategy.
    (package private) static final long[]
    An empty level 3 block is kept for use when scanning.
  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
     
    Constructs an empty bit set with the default initial size.
     
    SparseBitSet(int nbits)
    Creates a bit set whose initial size is large enough to efficiently represent bits with indices in the range 0 through at least nbits-1.
    protected
    SparseBitSet(int capacity, int compactionCount)
    Constructor for a new (sparse) bit set.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    and(int i, boolean value)
    Performs a logical AND of the addressed target bit with the argument value.
    void
    and(int i, int j, SparseBitSet b)
    Performs a logical AND of this target bit set with the argument bit set within the given range of bits.
    void
    Performs a logical AND of this target bit set with the argument bit set.
    Performs a logical AND of the two given SparseBitSets.
    void
    andNot(int i, boolean value)
    Performs a logical AndNOT of the addressed target bit with the argument value.
    void
    andNot(int i, int j, SparseBitSet b)
    Performs a logical AndNOT of this target bit set with the argument bit set within the given range of bits.
    void
    Performs a logical AndNOT of this target bit set with the argument bit set.
    Creates a bit set from thie first SparseBitSet whose corresponding bits are cleared by the set bits of the second SparseBitSet.
    int
    Returns the number of bits set to true in this SparseBitSet.
    void
    Sets all of the bits in this SparseBitSet to false.
    void
    clear(int i)
    Sets the bit at the specified index to false.
    void
    clear(int i, int j)
    Sets the bits from the specified i (inclusive) to the specified j (exclusive) to false.
    Cloning this SparseBitSet produces a new SparseBitSet that is equal() to it.
    protected final void
    Intializes all the additional objects required for correct operation.
    boolean
    Compares this object against the specified object.
    void
    flip(int i)
    Sets the bit at the specified index to the complement of its current value.
    void
    flip(int i, int j)
    Sets each bit from the specified i (inclusive) to the specified j (exclusive) to the complement of its current value.
    boolean
    get(int i)
    Returns the value of the bit with the specified index.
    get(int i, int j)
    Returns a new SparseBitSet composed of bits from this SparseBitSet from i (inclusive) to j (exclusive).
    int
    Returns a hash code value for this bit set.
    boolean
    intersects(int i, int j, SparseBitSet b)
    Returns true if the specified SparseBitSet has any bits within the given range i (inclusive) to j (exclusive) set to true that are also set to true in the same range of this SparseBitSet.
    boolean
    Returns true if the specified SparseBitSet has any bits set to true that are also set to true in this SparseBitSet.
    boolean
    Returns true if this SparseBitSet contains no bits that are set to true.
    int
    Returns the "logical length" of this SparseBitSet: the index of the highest set bit in the SparseBitSet plus one.
    int
    nextClearBit(int i)
    Returns the index of the first bit that is set to false that occurs on or after the specified starting index.
    int
    nextSetBit(int i)
    Returns the index of the first bit that is set to true that occurs on or after the specified starting index.
    protected final void
    nullify(int start)
    Clear out a part of the set array with nulls, from the given start to the end of the array.
    void
    or(int i, boolean value)
    Performs a logical OR of the addressed target bit with the argument value.
    void
    or(int i, int j, SparseBitSet b)
    Performs a logical OR of the addressed target bit with the argument value within the given range.
    void
    Performs a logical OR of this bit set with the bit set argument.
    Performs a logical OR of the two given SparseBitSets.
    int
    Returns the index of the nearest bit that is set to false that occurs on or before the specified starting index.
    int
    Returns the index of the nearest bit that is set to true that occurs on or before the specified starting index.
    private void
    Reconstitute the SparseBitSet instance from a stream (i.e., deserialize it).
    protected final void
    resize(int index)
    Resize the bit array.
    void
    set(int i)
    Sets the bit at the specified index.
    void
    set(int i, boolean value)
    Sets the bit at the specified index to the specified value.
    void
    set(int i, int j)
    Sets the bits from the specified i (inclusive) to the specified j (exclusive) to true.
    void
    set(int i, int j, boolean value)
    Sets the bits from the specified i (inclusive) to the specified j (exclusive) to the specified value.
    protected final void
    Scans over the bit set (and a second bit set if part of the operation) are all performed by this method.
    int
    Returns the number of bits of space nominally in use by this SparseBitSet to represent bit values.
    Convenience method for statistics if the individual results are not needed.
    statistics(String[] values)
    Determine, and create a String with the bit set statistics.
    protected final void
    The entirety of the bit set is examined, and the various statistics of the bit set (size, length, cardinality, hashCode, etc.) are computed.
    protected static void
    Throw the exception to indicate a range error.
    Returns a string representation of this bit set.
    void
    toStringCompaction(boolean change)
    If change is true, the current value of the toStringCompaction() value is made the default value for all SparseBitSets created from this point onward in this JVM.
    void
    toStringCompaction(int count)
    Sequences of set bits longer than this value are shown by toString() as a "sub-sequence," in the form a..b.
    private void
    Save the state of the SparseBitSet instance to a stream (i.e., serialize it).
    void
    xor(int i, boolean value)
    Performs a logical XOR of the addressed target bit with the argument value.
    void
    xor(int i, int j, SparseBitSet b)
    Performs a logical XOR of this bit set with the bit set argument within the given range.
    void
    Performs a logical XOR of this bit set with the bit set argument.
    Performs a logical XOR of the two given SparseBitSets.

    Methods inherited from class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait
  • Field Details

    • compactionCount

      protected transient int compactionCount
      This value controls for format of the toString() output.
      See Also:
    • compactionCountDefault

      static int compactionCountDefault
      The compaction count default.
    • bits

      protected transient long[][][] bits
      The storage for this SparseBitSet. The ith bit is stored in a word represented by a long value, and is at bit position i % 64 within that word (where bit position 0 refers to the least significant bit and 63 refers to the most significant bit).

      The words are organized into blocks, and the blocks are accessed by two additional levels of array indexing.

    • bitsLength

      protected transient int bitsLength
      For the current size of the bits array, this is the maximum possible length of the bit set, i.e., the index of the last possible bit, plus one. Note: this not the value returned by length().
      See Also:
    • LENGTH4

      protected static final int LENGTH4
      The number of bits in a long value.
      See Also:
    • INDEX_SIZE

      protected static final int INDEX_SIZE
      The number of bits in a positive integer, and the size of permitted index of a bit in the bit set.
      See Also:
    • LEVEL4

      protected static final int LEVEL4
      The label (index) of a bit in the bit set is essentially broken into 4 "levels". Respectively (from the least significant end), level4, the address within word, the address within a level3 block, the address within a level2 area, and the level1 address of that area within the set. LEVEL4 is the number of bits of the level4 address (number of bits need to address the bits in a long)
      See Also:
    • LEVEL3

      protected static final int LEVEL3
      LEVEL3 is the number of bits of the level3 address.
      See Also:
    • LEVEL2

      protected static final int LEVEL2
      LEVEL2 is the number of bits of the level2 address.
      See Also:
    • LEVEL1

      protected static final int LEVEL1
      LEVEL1 is the number of bits of the level1 address.
      See Also:
    • MAX_LENGTH1

      protected static final int MAX_LENGTH1
      MAX_LENGTH1 is the maximum number of entries in the level1 set array.
      See Also:
    • LENGTH2

      protected static final int LENGTH2
      LENGTH2 is the number of entries in the any level2 area.
      See Also:
    • LENGTH3

      protected static final int LENGTH3
      LENGTH3 is the number of entries in the any level3 block.
      See Also:
    • SHIFT3

      protected static final int SHIFT3
      The shift to create the word index. (I.e., move it to the right end)
      See Also:
    • MASK3

      protected static final int MASK3
      MASK3 is the mask to extract the LEVEL3 address from a word index (after shifting by SHIFT3).
      See Also:
    • SHIFT2

      protected static final int SHIFT2
      SHIFT2 is the shift to bring the level2 address (from the word index) to the right end (i.e., after shifting by SHIFT3).
      See Also:
    • UNIT

      protected static final int UNIT
      UNIT is the greatest number of bits that can be held in one level1 entry. That is, bits per word by words per level3 block by blocks per level2 area.
      See Also:
    • MASK2

      protected static final int MASK2
      MASK2 is the mask to extract the LEVEL2 address from a word index (after shifting by SHIFT3 and SHIFT2).
      See Also:
    • SHIFT1

      protected static final int SHIFT1
      SHIFT1 is the shift to bring the level1 address (from the word index) to the right end (i.e., after shifting by SHIFT3).
      See Also:
    • LENGTH2_SIZE

      protected static final int LENGTH2_SIZE
      LENGTH2_SIZE is maximum index of a LEVEL2 page.
      See Also:
    • LENGTH3_SIZE

      protected static final int LENGTH3_SIZE
      LENGTH3_SIZE is maximum index of a LEVEL3 page.
      See Also:
    • LENGTH4_SIZE

      protected static final int LENGTH4_SIZE
      LENGTH4_SIZE is maximum index of a bit in a LEVEL4 word.
      See Also:
    • cache

      protected transient SparseBitSet.Cache cache
      Holds reference to the cache of statistics values computed by the UpdateStrategy
      See Also:
    • spare

      protected transient long[] spare
      A spare level 3 block is kept for use when scanning. When a target block is needed, and there is not already one in the bit set, the spare is provided. If non-zero values are placed into this block, it is moved to the resulting set, and a new spare is acquired. Note: a new spare needs to be allocated when the set is cloned (so that the spare is not shared between two sets).
    • ZERO_BLOCK

      static final long[] ZERO_BLOCK
      An empty level 3 block is kept for use when scanning. When a source block is needed, and there is not already one in the corresponding bit set, the ZERO_BLOCK is used (as a read-only block). It is a source of zero values so that code does not have to test for a null level3 block. This is a static block shared everywhere.
    • serialVersionUID

      private static final long serialVersionUID
      serialVersionUID
      See Also:
    • andStrategy

      protected static final transient SparseBitSet.AndStrategy andStrategy
      Word and block and strategy.
    • andNotStrategy

      protected static final transient SparseBitSet.AndNotStrategy andNotStrategy
      Word and block andNot strategy.
    • clearStrategy

      protected static final transient SparseBitSet.ClearStrategy clearStrategy
      Word and block clear strategy.
    • copyStrategy

      protected static final transient SparseBitSet.CopyStrategy copyStrategy
      Word and block copy strategy.
    • equalsStrategy

      protected transient SparseBitSet.EqualsStrategy equalsStrategy
      Word and block equals strategy.
    • flipStrategy

      protected static final transient SparseBitSet.FlipStrategy flipStrategy
      Word and block flip strategy.
    • intersectsStrategy

      protected static transient SparseBitSet.IntersectsStrategy intersectsStrategy
      Word and block intersects strategy.
    • orStrategy

      protected static final transient SparseBitSet.OrStrategy orStrategy
      Word and block or strategy.
    • setStrategy

      protected static final transient SparseBitSet.SetStrategy setStrategy
      Word and block set strategy.
    • updateStrategy

      protected transient SparseBitSet.UpdateStrategy updateStrategy
      Word and block update strategy.
    • xorStrategy

      protected static final transient SparseBitSet.XorStrategy xorStrategy
      Word and block xor strategy.
  • Constructor Details

    • SparseBitSet

      protected SparseBitSet(int capacity, int compactionCount) throws NegativeArraySizeException
      Constructor for a new (sparse) bit set. All bits initially are effectively false. This is a internal constructor that collects all the needed actions to initialise the bit set.

      The capacity is taken to be a suggestion for a size of the bit set, in bits. An appropiate table size (a power of two) is then determined and used. The size will be grown as needed to accomodate any bits addressed during the use of the bit set.

      Parameters:
      capacity - a size in terms of bits
      compactionCount - the compactionCount to be inherited (for internal generation)
      Throws:
      NegativeArraySizeException - if the specified initial size is negative
      Since:
      1.6
    • SparseBitSet

      public SparseBitSet()
      Constructs an empty bit set with the default initial size. Initially all bits are effectively false.
      Since:
      1.6
    • SparseBitSet

      public SparseBitSet(int nbits) throws NegativeArraySizeException
      Creates a bit set whose initial size is large enough to efficiently represent bits with indices in the range 0 through at least nbits-1. Initially all bits are effectively false.

      No guarantees are given for how large or small the actual object will be. The setting of bits above the given range is permitted (and will perhaps eventually cause resizing).

      Parameters:
      nbits - the initial provisional length of the SparseBitSet
      Throws:
      NegativeArraySizeException - if the specified initial length is negative
      Since:
      1.6
      See Also:
  • Method Details

    • and

      public void and(int i, boolean value) throws IndexOutOfBoundsException
      Performs a logical AND of the addressed target bit with the argument value. This bit set is modified so that the addressed bit has the value true if and only if it both initially had the value true and the argument value is also true.
      Parameters:
      i - a bit index
      value - a boolean value to AND with that bit
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • and

      public void and(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
      Performs a logical AND of this target bit set with the argument bit set within the given range of bits. Within the range, 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. Outside the range, this set is not changed.
      Parameters:
      i - index of the first bit to be included in the operation
      j - index after the last bit to included in the operation
      b - a SparseBitSet
      Throws:
      IndexOutOfBoundsException - if i is negative or equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • and

      public void and(SparseBitSet b)
      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:
      b - a SparseBitSet
      Since:
      1.6
    • and

      public static SparseBitSet and(SparseBitSet a, SparseBitSet b)
      Performs a logical AND of the two given SparseBitSets. The returned SparseBitSet is created so that each bit in it has the value true if and only if both the given sets initially had the corresponding bits true, otherwise false.
      Parameters:
      a - a SparseBitSet
      b - another SparseBitSet
      Returns:
      a new SparseBitSet representing the AND of the two sets
      Since:
      1.6
    • andNot

      public void andNot(int i, boolean value)
      Performs a logical AndNOT of the addressed target bit with the argument value. This bit set is modified so that the addressed bit has the value true if and only if it both initially had the value true and the argument value is false.
      Parameters:
      i - a bit index
      value - a boolean value to AndNOT with that bit
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • andNot

      public void andNot(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
      Performs a logical AndNOT of this target bit set with the argument bit set within the given range of bits. Within the range, 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 has the value false. Outside the range, this set is not changed.
      Parameters:
      i - index of the first bit to be included in the operation
      j - index after the last bit to included in the operation
      b - the SparseBitSet with which to mask this SparseBitSet
      Throws:
      IndexOutOfBoundsException - if i is negative or equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • andNot

      public void andNot(SparseBitSet b)
      Performs a logical AndNOT 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 has the value false.
      Parameters:
      b - the SparseBitSet with which to mask this SparseBitSet
      Since:
      1.6
    • andNot

      public static SparseBitSet andNot(SparseBitSet a, SparseBitSet b)
      Creates a bit set from thie first SparseBitSet whose corresponding bits are cleared by the set bits of the second SparseBitSet. The resulting bit set is created so that a bit in it has the value true if and only if the corresponding bit in the SparseBitSet of the first is set, and that same corresponding bit is not set in the SparseBitSet of the second argument.
      Parameters:
      a - a SparseBitSet
      b - another SparseBitSet
      Returns:
      a new SparseBitSet representing the AndNOT of the two sets
      Since:
      1.6
    • cardinality

      public int cardinality()
      Returns the number of bits set to true in this SparseBitSet.
      Returns:
      the number of bits set to true in this SparseBitSet
      Since:
      1.6
    • clear

      public void clear(int i)
      Sets the bit at the specified index to false.
      Parameters:
      i - a bit index.
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE.
      Since:
      1.6
    • clear

      public void clear(int i, int j) throws IndexOutOfBoundsException
      Sets the bits from the specified i (inclusive) to the specified j (exclusive) to false.
      Parameters:
      i - index of the first bit to be cleared
      j - index after the last bit to be cleared
      Throws:
      IndexOutOfBoundsException - if i is negative or equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • clear

      public void clear()
      Sets all of the bits in this SparseBitSet to false.
      Since:
      1.6
    • clone

      public SparseBitSet clone()
      Cloning this SparseBitSet produces a new SparseBitSet 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.

      Note: the actual space allocated to the clone tries to minimise the actual amount of storage allocated to hold the bits, while still trying to keep access to the bits being a rapid as possible. Since the space allocated to a SparseBitSet is not normally decreased, replacing a bit set by its clone may be a way of both managing memory consumption and improving the rapidity of access.

      Overrides:
      clone in class Object
      Returns:
      a clone of this SparseBitSet
      Since:
      1.6
    • 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 SparseBitSet object that has exactly the same bits set to true as this bit set. That is, for every nonnegative i indexing a bit in the set,
      ((SparseBitSet)obj).get(i) == this.get(i)
      must be true.
      Overrides:
      equals in class Object
      Parameters:
      obj - the Object with which to compare
      Returns:
      true if the objects are equivalent; false otherwise.
      Since:
      1.6
    • flip

      public void flip(int i)
      Sets the bit at the specified index to the complement of its current value.
      Parameters:
      i - the index of the bit to flip
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • flip

      public void flip(int i, int j) throws IndexOutOfBoundsException
      Sets each bit from the specified i (inclusive) to the specified j (exclusive) to the complement of its current value.
      Parameters:
      i - index of the first bit to flip
      j - index after the last bit to flip
      Throws:
      IndexOutOfBoundsException - if i is negative or is equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • get

      public boolean get(int i)
      Returns the value of the bit with the specified index. The value is true if the bit with the index i is currently set in this SparseBitSet; otherwise, the result is false.
      Parameters:
      i - the bit index
      Returns:
      the boolean value of the bit with the specified index.
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • get

      public SparseBitSet get(int i, int j) throws IndexOutOfBoundsException
      Returns a new SparseBitSet composed of bits from this SparseBitSet from i (inclusive) to j (exclusive).
      Parameters:
      i - index of the first bit to include
      j - index after the last bit to include
      Returns:
      a new SparseBitSet from a range of this SparseBitSet
      Throws:
      IndexOutOfBoundsException - if i is negative or is equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • 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 SparseBitSet. The algorithm used to compute it may be described as follows.

      Suppose the bits in the SparseBitSet were to be stored in an array of long integers called, say, bits, in such a manner that bit i is set in the SparseBitSet (for nonnegative values of i) if and only if the expression

        ((i>>6) < bits.length) && ((bits[i>>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 hash = 1234L;
            for( int i = bits.length; --i >= 0; )
                hash ^= bits[i] * (i + 1);
            return (int)((h >> 32) ^ h);
        }
      Note that the hash code values change if the set of bits is altered.
      Overrides:
      hashCode in class Object
      Returns:
      a hash code value for this bit set
      Since:
      1.6
      See Also:
    • intersects

      public boolean intersects(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
      Returns true if the specified SparseBitSet has any bits within the given range i (inclusive) to j (exclusive) set to true that are also set to true in the same range of this SparseBitSet.
      Parameters:
      i - index of the first bit to include
      j - index after the last bit to include
      b - the SparseBitSet with which to intersect
      Returns:
      the boolean indicating whether this SparseBitSet intersects the specified SparseBitSet
      Throws:
      IndexOutOfBoundsException - if i is negative or equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • intersects

      public boolean intersects(SparseBitSet b)
      Returns true if the specified SparseBitSet has any bits set to true that are also set to true in this SparseBitSet.
      Parameters:
      b - a SparseBitSet with which to intersect
      Returns:
      boolean indicating whether this SparseBitSet intersects the specified SparseBitSet
      Since:
      1.6
    • isEmpty

      public boolean isEmpty()
      Returns true if this SparseBitSet contains no bits that are set to true.
      Returns:
      the boolean indicating whether this SparseBitSet is empty
      Since:
      1.6
    • length

      public int length()
      Returns the "logical length" of this SparseBitSet: the index of the highest set bit in the SparseBitSet plus one. Returns zero if the SparseBitSet contains no set bits.
      Returns:
      the logical length of this SparseBitSet
      Since:
      1.6
    • nextClearBit

      public int nextClearBit(int i)
      Returns the index of the first bit that is set to false that occurs on or after the specified starting index.
      Parameters:
      i - the index to start checking from (inclusive)
      Returns:
      the index of the next clear bit, or -1 if there is no such bit
      Throws:
      IndexOutOfBoundsException - if the specified index is negative
      Since:
      1.6
    • nextSetBit

      public int nextSetBit(int i)
      Returns the index of the first bit that is set to true that occurs on or after the specified starting index. If no such it exists then -1 is returned.

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

        for( int i = sbbits.nextSetBit(0); i >= 0; i = sbbits.nextSetBit(i+1) )
        {
            // operate on index i here
        }
      Parameters:
      i - the index to start checking from (inclusive)
      Returns:
      the index of the next set bit
      Throws:
      IndexOutOfBoundsException - if the specified index is negative
      Since:
      1.6
    • previousClearBit

      public int previousClearBit(int i)
      Returns the index of the nearest bit that is set to false 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:
      i - 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:
      1.2
      See Also:
    • previousSetBit

      public int previousSetBit(int i)
      Returns the index of the nearest bit that is set to true 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:
      i - 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:
      1.2
      See Also:
    • or

      public void or(int i, boolean value)
      Performs a logical OR of the addressed target bit with the argument value. This bit set is modified so that the addressed bit has the value true if and only if it both initially had the value true or the argument value is true.
      Parameters:
      i - a bit index
      value - a boolean value to OR with that bit
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • or

      public void or(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
      Performs a logical OR of the addressed target bit with the argument value within the given range. This bit set is modified so that within the range 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. Outside the range this set is not changed.
      Parameters:
      i - index of the first bit to be included in the operation
      j - index after the last bit to included in the operation
      b - the SparseBitSet with which to perform the OR operation with this SparseBitSet
      Throws:
      IndexOutOfBoundsException - if i is negative or equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • or

      public void or(SparseBitSet b)
      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:
      b - the SparseBitSet with which to perform the OR operation with this SparseBitSet
      Since:
      1.6
    • or

      public static SparseBitSet or(SparseBitSet a, SparseBitSet b)
      Performs a logical OR of the two given SparseBitSets. The returned SparseBitSet is created so that a bit in it has the value true if and only if it either had the value true in the set given by the first arguemetn or had the value true in the second argument, otherwise false.
      Parameters:
      a - a SparseBitSet
      b - another SparseBitSet
      Returns:
      new SparseBitSet representing the OR of the two sets
      Since:
      1.6
    • set

      public void set(int i)
      Sets the bit at the specified index.
      Parameters:
      i - a bit index
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • set

      public void set(int i, boolean value)
      Sets the bit at the specified index to the specified value.
      Parameters:
      i - a bit index
      value - a boolean value to set
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • set

      public void set(int i, int j) throws IndexOutOfBoundsException
      Sets the bits from the specified i (inclusive) to the specified j (exclusive) to true.
      Parameters:
      i - index of the first bit to be set
      j - index after the last bit to be se
      Throws:
      IndexOutOfBoundsException - if i is negative or is equal to Integer.MAX_INT, or j is negative, or i is larger than j.
      Since:
      1.6
    • set

      public void set(int i, int j, boolean value)
      Sets the bits from the specified i (inclusive) to the specified j (exclusive) to the specified value.
      Parameters:
      i - index of the first bit to be set
      j - index after the last bit to be set
      value - to which to set the selected bits
      Throws:
      IndexOutOfBoundsException - if i is negative or is equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • size

      public int size()
      Returns the number of bits of space nominally in use by this SparseBitSet to represent bit values. The count of bits in the set is the (label of the last set bit) + 1 - (the label of the first set bit).
      Returns:
      the number of bits (true and false) nominally in this bit set at this moment
      Since:
      1.6
    • statistics

      public String statistics()
      Convenience method for statistics if the individual results are not needed.
      Returns:
      a String detailing the statistics of the bit set
      Since:
      1.6
      See Also:
    • statistics

      public String statistics(String[] values)
      Determine, and create a String with the bit set statistics. The statistics include: Size, Length, Cardinality, Total words (i.e., the total number of 64-bit "words"), Set array length (i.e., the number of references that can be held by the top level array, Level2 areas in use, Level3 blocks in use,, Level2 pool size, Level3 pool size, and the Compaction count.

      This method is intended for diagnostic use (as it is relatively expensive in time), but can be useful in understanding an application's use of a SparseBitSet.

      Parameters:
      values - an array for the individual results (if not null)
      Returns:
      a String detailing the statistics of the bit set
      Since:
      1.6
    • toString

      public String toString()
      Returns a string representation of this bit set. For every index for which this SparseBitSet 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. If there is a subsequence of set bits longer than the value given by toStringCompaction, the subsequence is represented by the value for the first and the last values, with ".." between them. The individual bits, or the representation of sub-sequences are separated by ", " (a comma and a space) and surrounded by braces, resulting in a compact string showing (a variant of) the usual mathematical notation for a set of integers.
      Example (with the default value of 2 for subsequences):
            SparseBitSet drPepper = new SparseBitSet();
        
      Now drPepper.toString() returns "{}".
            drPepper.set(2);
        
      Now drPepper.toString() returns "{2}".
            drPepper.set(3, 4);
            drPepper.set(10);
        
      Now drPepper.toString() returns "{2..4, 10}".
      This method is intended for diagnostic use (as it is relatively expensive in time), but can be useful in interpreting problems in an application's use of a SparseBitSet.
      Overrides:
      toString in class Object
      Returns:
      a String representation of this SparseBitSet
      Since:
      1.6
      See Also:
    • toStringCompaction

      public void toStringCompaction(int count)
      Sequences of set bits longer than this value are shown by toString() as a "sub-sequence," in the form a..b. Setting this value to zero causes each set bit to be listed individually. The default default value is 2 (which means sequences of three or more bits set are shown as a subsequence, and all other set bits are listed individually).

      Note: this value will be passed to SparseBitSets that may be created within or as a result of the operations on this bit set, or, for static methods, from the value belonging to the first parameter.

      Parameters:
      count - the maximum count of a run of bits that are shown as individual entries in a toString() conversion. If 0, all bits are shown individually.
      Since:
      1.6
      See Also:
    • toStringCompaction

      public void toStringCompaction(boolean change)
      If change is true, the current value of the toStringCompaction() value is made the default value for all SparseBitSets created from this point onward in this JVM.
      Parameters:
      change - if true, change the default value
      Since:
      1.6
    • xor

      public void xor(int i, boolean value)
      Performs a logical XOR of the addressed target bit with the argument value. This bit set is modified so that the addressed bit has the value true if and only one of the following statements holds:
      • The addressed bit initially had the value true, and the value of the argument is false.
      • The bit initially had the value false, and the value of the argument is true.
      Parameters:
      i - a bit index
      value - a boolean value to XOR with that bit
      Throws:
      IndexOutOfBoundsException - if the specified index is negative or equal to Integer.MAX_VALUE
      Since:
      1.6
    • xor

      public void xor(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
      Performs a logical XOR of this bit set with the bit set argument within the given range. This resulting bit set is computed so that a bit within the range in it has the value true if and only if one of the following statements holds:
      • The bit initially had the value true, and the corresponding bit in the argument set has the value false.
      • The bit initially had the value false, and the corresponding bit in the argument set has the value true.
      Outside the range this set is not changed.
      Parameters:
      i - index of the first bit to be included in the operation
      j - index after the last bit to included in the operation
      b - the SparseBitSet with which to perform the XOR operation with this SparseBitSet
      Throws:
      IndexOutOfBoundsException - if i is negative or equal to Integer.MAX_VALUE, or j is negative, or i is larger than j
      Since:
      1.6
    • xor

      public void xor(SparseBitSet b)
      Performs a logical XOR of this bit set with the bit set argument. This resulting bit set is computed so that a bit in it has the value true if and only if one of the following statements holds:
      • The bit initially had the value true, and the corresponding bit in the argument set has the value false.
      • The bit initially had the value false, and the corresponding bit in the argument set has the value true.
      Parameters:
      b - the SparseBitSet with which to perform the XOR operation with thisSparseBitSet
      Since:
      1.6
    • xor

      public static SparseBitSet xor(SparseBitSet a, SparseBitSet b)
      Performs a logical XOR of the two given SparseBitSets. The resulting bit set is created so that a bit in it has the value true if and only if one of the following statements holds:
      • A bit in the first argument has the value true, and the corresponding bit in the second argument has the value false.
      • A bit in the first argument has the value false, and the corresponding bit in the second argument has the value true.
      Parameters:
      a - a SparseBitSet
      b - another SparseBitSet
      Returns:
      a new SparseBitSet representing the XOR of the two sets
      Since:
      1.6
    • throwIndexOutOfBoundsException

      protected static void throwIndexOutOfBoundsException(int i, int j) throws IndexOutOfBoundsException
      Throw the exception to indicate a range error. The String constructed reports all the possible errors in one message.
      Parameters:
      i - lower bound for a operation
      j - upper bound for a operation
      Throws:
      IndexOutOfBoundsException - indicating the range is not valid
      Since:
      1.6
    • constructorHelper

      protected final void constructorHelper()
      Intializes all the additional objects required for correct operation.
      Since:
      1.6
    • nullify

      protected final void nullify(int start)
      Clear out a part of the set array with nulls, from the given start to the end of the array. If the given parameter is beyond the end of the bits array, nothing is changed.
      Parameters:
      start - word index at which to start (inclusive)
      Since:
      1.6
    • resize

      protected final void resize(int index)
      Resize the bit array. Moves the entries in the the bits array of this SparseBitSet into an array whose size (which may be larger or smaller) is the given bit size (i.e., includes the bit whose index is one less that the given value). If the new array is smaller, the excess entries in the set array are discarded. If the new array is bigger, it is filled with nulls.
      Parameters:
      index - the desired address to be included in the set
      Since:
      1.6
    • setScanner

      protected final void setScanner(int i, int j, SparseBitSet b, SparseBitSet.AbstractStrategy op) throws IndexOutOfBoundsException
      Scans over the bit set (and a second bit set if part of the operation) are all performed by this method. The properties and the operation executed are defined by a given strategy, which must be derived from the AbstractStrategy. The strategy defines how to operate on a single word, and on whole words that may or may not constitute a full block of words.
      Parameters:
      i - the bit (inclusive) at which to start the scan
      j - the bit (exclusive) at which to stop the scan
      b - a SparseBitSet, if needed, the second SparseBitSet in the operation
      op - the AbstractStrategy class defining the operation to be executed
      Throws:
      IndexOutOfBoundsException
      Since:
      1.6
      See Also:
    • statisticsUpdate

      protected final void statisticsUpdate()
      The entirety of the bit set is examined, and the various statistics of the bit set (size, length, cardinality, hashCode, etc.) are computed. Level arrays that are empty (i.e., all zero at level 3, all null at level 2) are replaced by null references, ensuring a normalized representation.
      Since:
      1.6
    • writeObject

      private void writeObject(ObjectOutputStream s) throws IOException, InternalError
      Save the state of the SparseBitSet instance to a stream (i.e., serialize it).
      Parameters:
      s - the ObjectOutputStream to which to write the serialized object
      Throws:
      IOException - if an io error occurs
      InternalError - if the SparseBitSet representation is inconsistent
      Since:
      1.6
    • readObject

      private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException
      Reconstitute the SparseBitSet instance from a stream (i.e., deserialize it).
      Parameters:
      s - the ObjectInputStream to use
      Throws:
      IOException - if there is an io error
      ClassNotFoundException - if the stream contains an unidentified class
      Since:
      1.6