CountingBloomFilter (TomP2P Core 5.0-Beta1 API)

java.lang.Object
- net.tomp2p.rpc.CountingBloomFilter<E>

Type Parameters:
E - The type of object the BloomFilter should contain

All Implemented Interfaces:

Serializable, Iterable<E>, Collection<E>, Set<E>
```
public class CountingBloomFilter<E>
extends Object
implements Set<E>, Serializable
```
A counting Bloom Filter (see http://en.wikipedia.org/wiki/Bloom_filter) that uses java.util.Random as a primitive hash function, and which implements Java's Set interface for convenience. Only the add(), addAll(), contains(), and containsAll() methods are implemented. Calling any other method will yield an UnsupportedOperationException. This code may be used, modified, and redistributed provided that the author tag below remains intact.

Author:

Ian Clarke , Thomas Bocek Made a counting bloomfliter based on the simple bloom filter.

See Also:
Serialized Form

Constructor Summary

Constructors
Constructor and Description

CountingBloomFilter(int expectedElements, int[] intSet)
Constructs a CountingBloomFilter out of existing data.

Constructors
Constructor and Description
`CountingBloomFilter(int expectedElements, int[] intSet)` Constructs a CountingBloomFilter out of existing data.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`add(E o)`
`boolean`	`addAll(Collection<? extends E> c)`
`int`	`approximateCount(E key)` Returns the number of times that an element has been added.
`void`	`clear()` Clear the Bloom Filter
`boolean`	`contains(Object o)`
`boolean`	`containsAll(Collection<?> c)`
`boolean`	`equals(Object obj)`
`int`	`expectedElements()` Returns the expected elements that was provided by the user.
`double`	`expectedFalsePositiveProbability()` Calculates the approximate probability of the contains() method returning true for an object that had not previously been inserted into the bloom filter.
`int`	`hashCode()`
`int[]`	`intSet()` Returns the bitset that backs the bloom filter
`boolean`	`isEmpty()` Not implemented
`Iterator<E>`	`iterator()` Not implemented
`boolean`	`remove(Object o)` Not implemented
`boolean`	`removeAll(Collection<?> c)` Not implemented
`boolean`	`retainAll(Collection<?> c)` Not implemented
`int`	`size()` Not implemented
`Object[]`	`toArray()` Not implemented
`<T> T[]`	`toArray(T[] a)` Not implemented
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - CountingBloomFilter
```
public CountingBloomFilter(int expectedElements,
                   int[] intSet)
```
    Constructs a CountingBloomFilter out of existing data. You must specify the number of bits in the Bloom Filter, and also you should specify the number of items you expect to add. The latter is used to choose some optimal internal values to minimize the false-positive rate (which can be estimated with expectedFalsePositiveRate()).
    
    Parameters:
    expectedElements - he typical number of items you expect to be added to the CountingBloomFilter (often called 'n').
    intSet - The data that will be used in the backing BitSet
- Method Detail
  - expectedFalsePositiveProbability
```
public double expectedFalsePositiveProbability()
```
    Calculates the approximate probability of the contains() method returning true for an object that had not previously been inserted into the bloom filter. This is known as the "false positive probability".
    
    Returns:
    The estimated false positive rate
  - expectedElements
```
public int expectedElements()
```
    Returns the expected elements that was provided by the user.
    
    Returns:
    The expected elements that was provided by the user
  - add
```
public boolean add(E o)
```
    Specified by:
    
    add in interface Collection<E>
    
    Specified by:
    
    add in interface Set<E>
  - addAll
```
public boolean addAll(Collection<? extends E> c)
```
    Specified by:
    
    addAll in interface Collection<E>
    
    Specified by:
    
    addAll in interface Set<E>
    
    Parameters:
    c - The collection to add
    
    Returns:
    This method will always return false
  - clear
```
public void clear()
```
    Clear the Bloom Filter
    
    Specified by:
    
    clear in interface Collection<E>
    
    Specified by:
    
    clear in interface Set<E>
  - contains
```
public boolean contains(Object o)
```
    Specified by:
    
    contains in interface Collection<E>
    
    Specified by:
    
    contains in interface Set<E>
    
    Parameters:
    o - The object to compare
    
    Returns:
    False indicates that o was definitely not added to this Bloom Filter, true indicates that it probably was. The probability can be estimated using the expectedFalsePositiveProbability() method.
  - containsAll
```
public boolean containsAll(Collection<?> c)
```
    Specified by:
    
    containsAll in interface Collection<E>
    
    Specified by:
    
    containsAll in interface Set<E>
    
    Parameters:
    c - The collection to check if its inside this bloom filter
    
    Returns:
    true if the collection contains all the values
  - isEmpty
```
public boolean isEmpty()
```
    Not implemented
    
    Specified by:
    
    isEmpty in interface Collection<E>
    
    Specified by:
    
    isEmpty in interface Set<E>
  - iterator
```
public Iterator<E> iterator()
```
    Not implemented
    
    Specified by:
    
    iterator in interface Iterable<E>
    
    Specified by:
    
    iterator in interface Collection<E>
    
    Specified by:
    
    iterator in interface Set<E>
  - remove
```
public boolean remove(Object o)
```
    Not implemented
    
    Specified by:
    
    remove in interface Collection<E>
    
    Specified by:
    
    remove in interface Set<E>
  - removeAll
```
public boolean removeAll(Collection<?> c)
```
    Not implemented
    
    Specified by:
    
    removeAll in interface Collection<E>
    
    Specified by:
    
    removeAll in interface Set<E>
  - retainAll
```
public boolean retainAll(Collection<?> c)
```
    Not implemented
    
    Specified by:
    
    retainAll in interface Collection<E>
    
    Specified by:
    
    retainAll in interface Set<E>
  - size
```
public int size()
```
    Not implemented
    
    Specified by:
    
    size in interface Collection<E>
    
    Specified by:
    
    size in interface Set<E>
  - toArray
```
public Object[] toArray()
```
    Not implemented
    
    Specified by:
    
    toArray in interface Collection<E>
    
    Specified by:
    
    toArray in interface Set<E>
  - toArray
```
public <T> T[] toArray(T[] a)
```
    Not implemented
    
    Specified by:
    
    toArray in interface Collection<E>
    
    Specified by:
    
    toArray in interface Set<E>
  - intSet
```
public int[] intSet()
```
    Returns the bitset that backs the bloom filter
    
    Returns:
    bloom filter as a bitset
  - approximateCount
```
public int approximateCount(E key)
```
    Returns the number of times that an element has been added. This is an approximate value and can be larger but never smaller than the actual number of additions.
    
    Parameters:
    key - The key to count
    
    Returns:
    The number of approximate additions of this object
  - equals
```
public boolean equals(Object obj)
```
    Specified by:
    
    equals in interface Collection<E>
    
    Specified by:
    
    equals in interface Set<E>
    
    Overrides:
    
    equals in class Object
  - hashCode
```
public int hashCode()
```
    Specified by:
    
    hashCode in interface Collection<E>
    
    Specified by:
    
    hashCode in interface Set<E>
    
    Overrides:
    
    hashCode in class Object
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class CountingBloomFilter<E>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

CountingBloomFilter

Method Detail

expectedFalsePositiveProbability

expectedElements

add

addAll

clear

contains

containsAll

isEmpty

iterator

remove

removeAll

retainAll

size

toArray

toArray

intSet

approximateCount

equals

hashCode

toString