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

All Implemented Interfaces:

Cloneable, Bits
```
public final class BitVector
extends Object
implements Cloneable, Bits
```
Optimized implementation of a vector of bits. This is more-or-less like java.util.BitSet, but also includes the following:
- a count() method, which efficiently computes the number of one bits;
- optimized read from and write to disk;
- inlinable get() method;
- store and load, as bit set or d-gaps, depending on sparseness;
NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Nested Class Summary
- Nested classes/interfaces inherited from interface org.apache.lucene.util.Bits
  Bits.MatchAllBits, Bits.MatchNoBits

Field Summary
- Fields inherited from interface org.apache.lucene.util.Bits
  EMPTY_ARRAY

Constructor Summary

Constructors
Constructor	Description
`BitVector(int n)`	Constructs a vector capable of holding `n` bits.
`BitVector(Directory d, String name)`	Constructs a bit vector from the file `name` in Directory `d`, as written by the `write(org.apache.lucene.store.Directory, java.lang.String)` method.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`clear(int bit)`	Sets the value of `bit` to zero.
`Object`	`clone()`
`int`	`count()`	Returns the total number of one bits in this vector.
`boolean`	`get(int bit)`	Returns `true` if `bit` is one and `false` if it is zero.
`boolean`	`getAndSet(int bit)`	Sets the value of `bit` to true, and returns true if bit was already set
`int`	`getRecomputedCount()`	For testing
`int`	`length()`	Returns the number of bits in this vector.
`void`	`set(int bit)`	Sets the value of `bit` to one.
`int`	`size()`	Returns the number of bits in this vector.
`void`	`write(Directory d, String name)`	Writes this vector to the file `name` in Directory `d`, in a format that can be read by the constructor `BitVector(Directory, String)`.

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - BitVector
```
public BitVector(int n)
```
    Constructs a vector capable of holding n bits.
  - BitVector
```
public BitVector(Directory d,
                 String name)
          throws IOException
```
    Constructs a bit vector from the file name in Directory d, as written by the write(org.apache.lucene.store.Directory, java.lang.String) method.
    
    Throws:
    
    IOException
- Method Detail
  - clone
```
public Object clone()
```
    Overrides:
    
    clone in class Object
  - set
```
public final void set(int bit)
```
    Sets the value of bit to one.
  - getAndSet
```
public final boolean getAndSet(int bit)
```
    Sets the value of bit to true, and returns true if bit was already set
  - clear
```
public final void clear(int bit)
```
    Sets the value of bit to zero.
  - get
```
public final boolean get(int bit)
```
    Returns true if bit is one and false if it is zero.
    
    Specified by:
    
    get in interface Bits
  - size
```
public final int size()
```
    Returns the number of bits in this vector. This is also one greater than the number of the largest valid bit number.
  - length
```
public final int length()
```
    Returns the number of bits in this vector. This is also one greater than the number of the largest valid bit number.
    
    Specified by:
    
    length in interface Bits
  - count
```
public final int count()
```
    Returns the total number of one bits in this vector. This is efficiently computed and cached, so that, if the vector is not changed, no recomputation is done for repeated calls.
  - getRecomputedCount
```
public final int getRecomputedCount()
```
    For testing
  - write
```
public final void write(Directory d,
                        String name)
                 throws IOException
```
    Writes this vector to the file name in Directory d, in a format that can be read by the constructor BitVector(Directory, String).
    
    Throws:
    
    IOException

Class BitVector

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.lucene.util.Bits

Field Summary

Fields inherited from interface org.apache.lucene.util.Bits

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

BitVector

BitVector

Method Detail

clone

set

getAndSet

clear

get

size

length

count

getRecomputedCount

write