public class WeakHashMap<K, V>

Object
WeakHashMap

Helper weak hash map substitute

Constructors

public WeakHashMap()

Methods

`public int size()`	Returns the number of mappings in this `Map`.
`public boolean isEmpty()`	Returns whether this map is empty.
`public boolean containsKey(Object key)`	Returns whether this `Map` contains the specified key.
`public boolean containsValue(Object value)`	This method is unsupported in the weak hash map
`public V get(Object key)`	Returns the value of the mapping with the specified key.
`public V put(K key, V value)`	Maps the specified key to the specified value.
`public V remove(Object key)`	Removes a mapping with the specified key from this `Map`.
`public void putAll(Map<? extends K, ? extends V> m)`	Copies every mapping in the specified `Map` to this `Map`.
`public void clear()`	Removes all elements from this `Map`, leaving it empty.
`public` `Set<K> keySet()`	Returns a set of the keys contained in this `Map`.
`public` `Collection<V> values()`	Unsupported operation
`public` `Set<Map.Entry<K, V>> entrySet()`	Unsupported operation

Inherited nested types

From Map

Map.Entry

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone

From Map

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

Constructor details

WeakHashMap

public WeakHashMap()

Method details

size

public int size()

Returns the number of mappings in this Map.

Returns

the number of mappings in this Map.

isEmpty

public boolean isEmpty()

Returns whether this map is empty.

Returns

true if this map has no elements, false otherwise.

containsKey

public boolean containsKey(Object key)

Returns whether this Map contains the specified key.

Parameters

key Object: the key to search for.

Returns

true if this map contains the specified key, false otherwise.

containsValue

public boolean containsValue(Object value)

This method is unsupported in the weak hash map

Parameters

value Object: the value to search for.

Returns

true if this map contains the specified value, false otherwise.

get

public V get(Object key)

Returns the value of the mapping with the specified key.

Parameters

key Object: the key.

Returns

the value of the mapping with the specified key, or null if no mapping for the specified key is found.

put

public V put(K key, V value)

Maps the specified key to the specified value.

Parameters

key K: the key.
value V: the value.

Returns

the value of any previous mapping with the specified key or null if there was no mapping.

Throws

UnsupportedOperationException: if adding to this Map is not supported.
ClassCastException: if the class of the key or value is inappropriate for this Map.
IllegalArgumentException: if the key or value cannot be added to this Map.
NullPointerException: if the key or value is null and this Map does not support null keys or values.

remove

public V remove(Object key)

Removes a mapping with the specified key from this Map.

Parameters

key Object: the key of the mapping to remove.

Returns

the value of the removed mapping or null if no mapping for the specified key was found.

Throws

UnsupportedOperationException: if removing from this Map is not supported.

putAll

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

Copies every mapping in the specified Map to this Map.

Parameters

m Map<? extends K, ? extends V>: the Map to copy mappings from.

Throws

UnsupportedOperationException: if adding to this Map is not supported.
ClassCastException: if the class of a key or a value of the specified Map is inappropriate for this Map.
IllegalArgumentException: if a key or value cannot be added to this Map.
NullPointerException: if a key or value is null and this Map does not support null keys or values.

clear

public void clear()

Removes all elements from this Map, leaving it empty.

Throws

UnsupportedOperationException: if removing elements from this Map is not supported.

keySet

public Set<K> keySet()

Returns a set of the keys contained in this Map. The Set is backed by this Map so changes to one are reflected by the other. The Set does not support adding.

Returns

a set of the keys.

values

public Collection<V> values()

Unsupported operation

Returns

a collection of the values contained in this map.

entrySet

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

Unsupported operation

Returns

a set of the mappings