org.apache.lucene.util

## Class LongBitSet

- java.lang.Object
- - org.apache.lucene.util.LongBitSet

-     public final class LongBitSet
      extends Object

  BitSet of fixed length (numBits), backed by accessible (`getBits()`) long[], accessed with a long index. Use it only if you intend to store more than 2.1B bits, otherwise you should use `FixedBitSet`.
  NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static long` | `MAX_NUM_BITS` The maximum `numBits` supported.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `LongBitSet(long numBits)` Creates a new LongBitSet.
    `LongBitSet(long[] storedBits, long numBits)` Creates a new LongBitSet using the provided long[] array as backing store.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `and(LongBitSet other)` this = this AND other
    `void` | `andNot(LongBitSet other)` this = this AND NOT other
    `static int` | `bits2words(long numBits)` Returns the number of 64 bit words it would take to hold numBits
    `long` | `cardinality()` Returns number of set bits.
    `void` | `clear(long index)`
    `void` | `clear(long startIndex, long endIndex)` Clears a range of bits.
    `LongBitSet` | `clone()`
    `static LongBitSet` | `ensureCapacity(LongBitSet bits, long numBits)` If the given `LongBitSet` is large enough to hold `numBits+1`, returns the given bits, otherwise returns a new `LongBitSet` which can hold the requested number of bits.
    `boolean` | `equals(Object o)` returns true if both sets have the same bits set
    `void` | `flip(long index)` Flip the bit at the provided index.
    `void` | `flip(long startIndex, long endIndex)` Flips a range of bits
    `boolean` | `get(long index)`
    `boolean` | `getAndClear(long index)`
    `boolean` | `getAndSet(long index)`
    `long[]` | `getBits()` Expert.
    `int` | `hashCode()`
    `boolean` | `intersects(LongBitSet other)` returns true if the sets have any elements in common
    `long` | `length()` Returns the number of bits stored in this bitset.
    `long` | `nextSetBit(long index)` Returns the index of the first set bit starting at the index specified.
    `void` | `or(LongBitSet other)` this = this OR other
    `long` | `prevSetBit(long index)` Returns the index of the last set bit before or on the index specified.
    `boolean` | `scanIsEmpty()` Scans the backing store to check if all bits are clear.
    `void` | `set(long index)`
    `void` | `set(long startIndex, long endIndex)` Sets a range of bits
    `void` | `xor(LongBitSet other)` this = this XOR other

    - ### Methods inherited from class java.lang.Object

      `finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### MAX_NUM_BITS

          public static final long MAX_NUM_BITS

      The maximum `numBits` supported.

  - ### Constructor Detail

    - #### LongBitSet

          public LongBitSet(long numBits)

      Creates a new LongBitSet. The internally allocated long array will be exactly the size needed to accommodate the numBits specified.
      Parameters:
        `numBits` - the number of bits needed

    - #### LongBitSet

          public LongBitSet(long[] storedBits,
                            long numBits)

      Creates a new LongBitSet using the provided long[] array as backing store. The storedBits array must be large enough to accommodate the numBits specified, but may be larger. In that case the 'extra' or 'ghost' bits must be clear (or they may provoke spurious side-effects)
      Parameters:
        `storedBits` - the array to use as backing store
        `numBits` - the number of bits actually needed

  - ### Method Detail

    - #### ensureCapacity

          public static LongBitSet ensureCapacity(LongBitSet bits,
                                                  long numBits)

      If the given `LongBitSet` is large enough to hold `numBits+1`, returns the given bits, otherwise returns a new `LongBitSet` which can hold the requested number of bits.

      NOTE: the returned bitset reuses the underlying `long[]` of the given `bits` if possible. Also, calling `length()` on the returned bits may return a value greater than `numBits`.

    - #### bits2words

          public static int bits2words(long numBits)

      Returns the number of 64 bit words it would take to hold numBits

    - #### length

          public long length()

      Returns the number of bits stored in this bitset.

    - #### getBits

          public long[] getBits()

      Expert.

    - #### cardinality

          public long cardinality()

      Returns number of set bits. NOTE: this visits every long in the backing bits array, and the result is not internally cached!

    - #### get

          public boolean get(long index)

    - #### set

          public void set(long index)

    - #### getAndSet

          public boolean getAndSet(long index)

    - #### clear

          public void clear(long index)

    - #### getAndClear

          public boolean getAndClear(long index)

    - #### nextSetBit

          public long nextSetBit(long index)

      Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.

    - #### prevSetBit

          public long prevSetBit(long index)

      Returns the index of the last set bit before or on the index specified. -1 is returned if there are no more set bits.

    - #### or

          public void or(LongBitSet other)

      this = this OR other

    - #### xor

          public void xor(LongBitSet other)

      this = this XOR other

    - #### intersects

          public boolean intersects(LongBitSet other)

      returns true if the sets have any elements in common

    - #### and

          public void and(LongBitSet other)

      this = this AND other

    - #### andNot

          public void andNot(LongBitSet other)

      this = this AND NOT other

    - #### scanIsEmpty

          public boolean scanIsEmpty()

      Scans the backing store to check if all bits are clear. The method is deliberately not called "isEmpty" to emphasize it is not low cost (as isEmpty usually is).
      Returns:
        true if all bits are clear.

    - #### flip

          public void flip(long startIndex,
                           long endIndex)

      Flips a range of bits
      Parameters:
        `startIndex` - lower index
        `endIndex` - one-past the last bit to flip

    - #### flip

          public void flip(long index)

      Flip the bit at the provided index.

    - #### set

          public void set(long startIndex,
                          long endIndex)

      Sets a range of bits
      Parameters:
        `startIndex` - lower index
        `endIndex` - one-past the last bit to set

    - #### clear

          public void clear(long startIndex,
                            long endIndex)

      Clears a range of bits.
      Parameters:
        `startIndex` - lower index
        `endIndex` - one-past the last bit to clear

    - #### clone

          public LongBitSet clone()

      Overrides:
        `clone` in class `Object`

    - #### equals

          public boolean equals(Object o)

      returns true if both sets have the same bits set
      Overrides:
        `equals` in class `Object`

    - #### hashCode

          public int hashCode()

      Overrides:
        `hashCode` in class `Object`

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