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java.lang.Object com.google.common.hash.BloomFilter<T>
T
 the type of instances that the BloomFilter
accepts@Beta public final class BloomFilter<T>
A Bloom filter for instances of T
. A Bloom filter offers an approximate containment test
with onesided error: if it claims that an element is contained in it, this might be in error,
but if it claims that an element is not contained in it, then this is definitely true.
If you are unfamiliar with Bloom filters, this nice tutorial may help you understand how they work.
Method Summary  

BloomFilter<T> 
copy()
Creates a new BloomFilter that's a copy of this instance. 

static

create(Funnel<T> funnel,
int expectedInsertions)
Creates a Builder of a BloomFilter , with the expected number
of insertions, and a default expected false positive probability of 3%. 

static

create(Funnel<T> funnel,
int expectedInsertions,
double falsePositiveProbability)
Creates a Builder of a BloomFilter , with the expected number
of insertions and expected false positive probability. 

boolean 
equals(Object o)


double 
expectedFalsePositiveProbability()
Returns the probability that mightContain(Object) will erroneously return true for an object that has not actually been put in the BloomFilter . 

int 
hashCode()


boolean 
mightContain(T object)
Returns true if the element might have been put in this Bloom filter,
false if this is definitely not the case. 

boolean 
put(T object)
Puts an element into this BloomFilter . 
Methods inherited from class java.lang.Object 

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait 
Method Detail 

public BloomFilter<T> copy()
BloomFilter
that's a copy of this instance. The new instance is equal to
this instance but shares no mutable state.
public boolean mightContain(T object)
true
if the element might have been put in this Bloom filter,
false
if this is definitely not the case.
public boolean put(T object)
BloomFilter
. Ensures that subsequent invocations of
mightContain(Object)
with the same element will always return true
.
object
has been added to the
filter. If the bits haven't changed, this might be the first time object
has been added to the filter. Note that put(t)
always returns the
opposite result to what mightContain(t)
would have returned at the time
it is called."void
return type})public double expectedFalsePositiveProbability()
true
for an object that has not actually been put in the BloomFilter
.
Ideally, this number should be close to the falsePositiveProbability
parameter
passed in create(Funnel, int, double), or smaller. If it is
significantly higher, it is usually the case that too many elements (more than
expected) have been put in the BloomFilter
, degenerating it.
public boolean equals(Object o)
This implementation uses reference equality to compare funnels.
equals
in class Object
public int hashCode()
hashCode
in class Object
public static <T> BloomFilter<T> create(Funnel<T> funnel, int expectedInsertions, double falsePositiveProbability)
Builder
of a BloomFilter
, with the expected number
of insertions and expected false positive probability.
Note that overflowing a BloomFilter
with significantly more elements
than specified, will result in its saturation, and a sharp deterioration of its
false positive probability.
The constructed BloomFilter<T>
will be serializable if the provided
Funnel<T>
is.
It is recommended the funnel is implemented as a Java enum. This has the benefit of ensuring
proper serialization and deserialization, which is important since equals(java.lang.Object)
also relies
on object identity of funnels.
funnel
 the funnel of T's that the constructed BloomFilter<T>
will useexpectedInsertions
 the number of expected insertions to the constructed
BloomFilter<T>
; must be positivefalsePositiveProbability
 the desired false positive probability (must be positive and
less than 1.0)
BloomFilter
public static <T> BloomFilter<T> create(Funnel<T> funnel, int expectedInsertions)
Builder
of a BloomFilter
, with the expected number
of insertions, and a default expected false positive probability of 3%.
Note that overflowing a BloomFilter
with significantly more elements
than specified, will result in its saturation, and a sharp deterioration of its
false positive probability.
The constructed BloomFilter<T>
will be serializable if the provided
Funnel<T>
is.
funnel
 the funnel of T's that the constructed BloomFilter<T>
will useexpectedInsertions
 the number of expected insertions to the constructed
BloomFilter<T>
; must be positive
BloomFilter


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