public class WeakHashMap<K,V> extends AbstractMap<K,V> implements Map<K,V>
HashMap
,
WeakReference
AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>
Constructor and Description |
---|
WeakHashMap()
Constructs a new empty
WeakHashMap instance. |
WeakHashMap(int capacity)
Constructs a new
WeakHashMap instance with the specified
capacity. |
WeakHashMap(int capacity,
float loadFactor)
Constructs a new
WeakHashMap instance with the specified capacity
and load factor. |
WeakHashMap(Map<? extends K,? extends V> map)
Constructs a new
WeakHashMap instance containing the mappings
from the specified map. |
Modifier and Type | Method and Description |
---|---|
void |
clear()
Removes all mappings from this map, leaving it empty.
|
boolean |
containsKey(Object key)
Returns whether this map contains the specified key.
|
boolean |
containsValue(Object value)
Returns whether this map contains the specified value.
|
Set<Map.Entry<K,V>> |
entrySet()
Returns a set containing all of the mappings in this map.
|
V |
get(Object key)
Returns the value of the mapping with the specified key.
|
boolean |
isEmpty()
Returns the number of elements in this map.
|
Set<K> |
keySet()
Returns a set of the keys contained in this map.
|
V |
put(K key,
V value)
Maps the specified key to the specified value.
|
void |
putAll(Map<? extends K,? extends V> map)
Copies all the mappings in the given map to this map.
|
V |
remove(Object key)
Removes the mapping with the specified key from this map.
|
int |
size()
Returns the number of elements in this map.
|
Collection<V> |
values()
Returns a collection of the values contained in this map.
|
clone, equals, hashCode, toString
public WeakHashMap()
WeakHashMap
instance.public WeakHashMap(int capacity)
WeakHashMap
instance with the specified
capacity.capacity
- the initial capacity of this map.IllegalArgumentException
- if the capacity is less than zero.public WeakHashMap(int capacity, float loadFactor)
WeakHashMap
instance with the specified capacity
and load factor.capacity
- the initial capacity of this map.loadFactor
- the initial load factor.IllegalArgumentException
- if the capacity is less than zero or the load factor is less
or equal to zero.public void clear()
public boolean containsKey(Object key)
containsKey
in interface Map<K,V>
containsKey
in class AbstractMap<K,V>
key
- the key to search for.true
if this map contains the specified key,
false
otherwise.public Set<Map.Entry<K,V>> entrySet()
Map.Entry
. As the set is backed by this map,
changes in one will be reflected in the other. It does not support adding
operations.public Set<K> keySet()
public Collection<V> values()
This method returns a collection which is the subclass of AbstractCollection. The iterator method of this subclass returns a "wrapper object" over the iterator of map's entrySet(). The size method wraps the map's size method and the contains method wraps the map's containsValue method.
The collection is created when this method is called at first time and returned in response to all subsequent calls. This method may return different Collection when multiple calls to this method, since it has no synchronization performed.
public boolean containsValue(Object value)
containsValue
in interface Map<K,V>
containsValue
in class AbstractMap<K,V>
value
- the value to search for.true
if this map contains the specified value,
false
otherwise.public boolean isEmpty()
isEmpty
in interface Map<K,V>
isEmpty
in class AbstractMap<K,V>
Map.size()
public void putAll(Map<? extends K,? extends V> map)
putAll
in interface Map<K,V>
putAll
in class AbstractMap<K,V>
map
- the map to copy mappings from.NullPointerException
- if map
is null
.