org.gudy.azureus2.core3.util
Class LightHashSet

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractSet
          org.gudy.azureus2.core3.util.LightHashSet

All Implemented Interfaces:

Cloneable, Iterable, Collection, Set

public class LightHashSet
extends AbstractSet
implements Cloneable

A lighter (on memory) hash set
Advantages over HashSet:

• Lower memory footprint
• Everything is stored in a single array, this might improve cache performance (not verified)
• Read-only operations on iterators should be concurrency-safe but they might return null values unexpectedly under concurrent modification (not verified)

Disadvantages:

• removal is implemented with thombstone-keys, this can significantly increase the lookup time if many values are removed. Use compactify() for scrubbing
• entry set iterators and thus transfers to other maps are slower than compareable implementations
• the map does not store hashcodes and relies on either the key-objects themselves caching them (such as strings) or a fast computation of hashcodes

Author:

Aaron Grunthal

Constructor Summary

LightHashSet()

LightHashSet(Collection c)

LightHashSet(int initialCapacity)

LightHashSet(int initialCapacity, float loadFactor)

Method Summary

boolean	add(Object key)
boolean	addAll(Collection c)
int	capacity()
void	clear()
Object	clone()
void	compactify(float compactingLoadFactor) will shrink the internal storage size to the least possible amount, should be used after removing many entries for example
boolean	contains(Object key)
Object	get(Object key) Fetches an element which does equal() the provided object but is not necessarily the same object
Iterator	iterator()
static void	main(String[] args)
boolean	remove(Object key)
int	size()

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

containsAll, isEmpty, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Set

containsAll, isEmpty, retainAll, toArray, toArray

Constructor Detail

LightHashSet

public LightHashSet()

LightHashSet

public LightHashSet(int initialCapacity)

LightHashSet

public LightHashSet(Collection c)

LightHashSet

public LightHashSet(int initialCapacity,
                    float loadFactor)

Method Detail

clone

public Object clone()

Overrides:

clone in class Object

iterator

public Iterator iterator()

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in interface Set

Specified by:

iterator in class AbstractCollection

add

public boolean add(Object key)

Specified by:

add in interface Collection

Specified by:

add in interface Set

Overrides:

add in class AbstractCollection

size

public int size()

Specified by:

size in interface Collection

Specified by:

size in interface Set

Specified by:

size in class AbstractCollection

addAll

public boolean addAll(Collection c)

Specified by:

addAll in interface Collection

Specified by:

addAll in interface Set

Overrides:

addAll in class AbstractCollection

capacity

public int capacity()

get

public Object get(Object key)

Fetches an element which does equal() the provided object but is not necessarily the same object

Parameters:

Object - to retrieve

Returns:

an object fulfilling the equals contract or null if no such object was found in this set

remove

public boolean remove(Object key)

Specified by:

remove in interface Collection

Specified by:

remove in interface Set

Overrides:

remove in class AbstractCollection

clear

public void clear()

Specified by:

clear in interface Collection

Specified by:

clear in interface Set

Overrides:

clear in class AbstractCollection

contains

public boolean contains(Object key)

Specified by:

contains in interface Collection

Specified by:

contains in interface Set

Overrides:

contains in class AbstractCollection

compactify

public void compactify(float compactingLoadFactor)

will shrink the internal storage size to the least possible amount, should be used after removing many entries for example

Parameters:

compactingLoadFactor - load factor for the compacting operation. Use 0f to compact with the load factor specified during instantiation. Use negative values of the desired load factors to compact only when it would reduce the storage size.

main

public static void main(String[] args)