T
 the type of instances that the BloomFilter
accepts@Beta public final class BloomFilter<T> extends Object implements Predicate<T>, Serializable
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.
The false positive probability (FPP
) of a bloom filter is defined as the probability
that mightContain(Object) will erroneously return true
for an object that
has not actually been put in the BloomFilter
.
Modifier and Type  Method and Description 

boolean 
apply(T input)
Equivalent to
mightContain(T) ; provided only to satisfy the Predicate interface. 
BloomFilter<T> 
copy()
Creates a new
BloomFilter that's a copy of this instance. 
static <T> BloomFilter<T> 
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 <T> BloomFilter<T> 
create(Funnel<T> funnel,
int expectedInsertions,
double fpp)
Creates a
Builder of a BloomFilter , with the expected number
of insertions and expected false positive probability. 
boolean 
equals(Object object)
Indicates whether another object is equal to this predicate.

double 
expectedFalsePositiveProbability()
Deprecated.
Use
expectedFpp() instead. 
double 
expectedFpp()
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 . 
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 apply(T input)
mightContain(T)
; provided only to satisfy the Predicate
interface.
When using a reference of type BloomFilter
, always invoke mightContain(T)
directly instead.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 expectedFpp()
true
for an object that has not actually been put in the BloomFilter
.
Ideally, this number should be close to the fpp
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.
@Deprecated public double expectedFalsePositiveProbability()
expectedFpp()
instead.public boolean equals(@Nullable Object object)
Predicate
Most implementations will have no reason to override the behavior of Object.equals(java.lang.Object)
.
However, an implementation may also choose to return true
whenever object
is a
Predicate
that it considers interchangeable with this one. "Interchangeable"
typically means that this.apply(t) == that.apply(t)
for all t
of type
T
). Note that a false
result from this method does not imply that the
predicates are known not to be interchangeable.
public static <T> BloomFilter<T> create(Funnel<T> funnel, int expectedInsertions, double fpp)
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 positivefpp
 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 positiveBloomFilter
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