Package com.jogamp.common.util

Class WeakIdentityHashMap<K,V>

java.lang.Object

com.jogamp.common.util.WeakIdentityHashMap<K,V>

All Implemented Interfaces:

Map<K,V>

public class WeakIdentityHashMap<K,V>
extends Object
implements Map<K,V>

Implements a combination of WeakHashMap and IdentityHashMap. Useful for caches that need to key off of a == comparison instead of a .equals. This class is not a general-purpose Map implementation! While this class implements the Map interface, it intentionally violates Map's general contract, which mandates the use of the equals method when comparing objects. This class is designed for use only in the rare cases wherein reference-equality semantics are required. Note that this implementation is not synchronized.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
WeakIdentityHashMap()	See HashMap()
WeakIdentityHashMap(int initialCapacity, float loadFactor)	See HashMap(int, float)

Method Summary

Modifier and Type	Method	Description
static int	capacityForRequiredSize(int requiredSize, float[] loadFactor)	Returns the [initial] capacity using the given loadFactor and requiredSize.
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
static WeakIdentityHashMap<?,?>	createWithRequiredSize(int requiredSize, float loadFactor)	Static creation method using capacityForRequiredSize(int, float[]) to instantiate a new WeakIdentityHashMap via WeakIdentityHashMap(int, float).
Set<Map.Entry<K,V>>	entrySet()
boolean	equals(Object o)
V	get(Object key)
int	hashCode()
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value)
void	putAll(Map<? extends K,? extends V> t)
V	remove(Object key)
int	size()
Collection<V>	values()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Detail

WeakIdentityHashMap

public WeakIdentityHashMap()

See HashMap()

WeakIdentityHashMap

public WeakIdentityHashMap(int initialCapacity,
                           float loadFactor)

See HashMap(int, float)

Usable slots before resize are capacity * loadFactor.

Capacity for n-slots w/o resize would be (float)n/loadFactor + 1.0f, see capacityForRequiredSize(int, float[]).

Parameters:

initialCapacity - default value would be 16, i.e. 12 slots @ 0.75f loadFactor before resize

loadFactor - default value would be 0.75f

See Also:

capacityForRequiredSize(int, float[]), createWithRequiredSize(int, float)

Method Detail

createWithRequiredSize

public static WeakIdentityHashMap<?,?> createWithRequiredSize(int requiredSize,
                                                                    float loadFactor)

Static creation method using capacityForRequiredSize(int, float[]) to instantiate a new WeakIdentityHashMap via WeakIdentityHashMap(int, float).

Parameters:

requiredSize - the user desired n-slots before resize

loadFactor - given loadFactor, which might be increased a little to avoid next PowerOf2 bloat

Returns:

the new WeakIdentityHashMap instance

capacityForRequiredSize

public static int capacityForRequiredSize(int requiredSize,
                                          float[] loadFactor)

Returns the [initial] capacity using the given loadFactor and requiredSize.

General calculation is (float)requiredSize/loadFactor + 1.0f, using loadFactor := 0.75f.

In case above computed capacity is Bitfield.Util.isPowerOf2(int), the given loadFactor will be increased to avoid next PowerOf2 table size initialization.

Parameters:

requiredSize - the user desired n-slots before resize

loadFactor - given loadFactor, which might be increased a little to avoid next PowerOf2 bloat

Returns:

the [initial] capacity to be used for WeakIdentityHashMap(int, float)

clear

public void clear()

Specified by:

clear in interface Map<K,V>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,V>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

entrySet

public Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Map<K,V>

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

equals

public boolean equals(Object o)

Specified by:

equals in interface Map<K,V>

Overrides:

equals in class Object

get

public V get(Object key)

Specified by:

get in interface Map<K,V>

put

public V put(K key,
             V value)

Specified by:

put in interface Map<K,V>

hashCode

public int hashCode()

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class Object

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

putAll

public void putAll(Map<? extends K,? extends V> t)

Specified by:

putAll in interface Map<K,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

size

public int size()

Specified by:

size in interface Map<K,V>

values

public Collection<V> values()

Specified by:

values in interface Map<K,V>