K - the type of keys maintained by this mapV - the type of mapped valuespublic final class ConcurrentWeakKeyHashMap<K,V> extends AbstractMap<K,V> implements ConcurrentMap<K,V>
ConcurrentMap which is similar to
ConcurrentHashMap.AbstractMap.SimpleImmutableEntry<K,V>| Constructor and Description |
|---|
ConcurrentWeakKeyHashMap()
Creates a new, empty map with a default initial capacity (16), reference
types (weak keys, strong values), default load factor (0.75) and
concurrencyLevel (16).
|
ConcurrentWeakKeyHashMap(int initialCapacity)
Creates a new, empty map with the specified initial capacity, and with
default reference types (weak keys, strong values), load factor (0.75)
and concurrencyLevel (16).
|
ConcurrentWeakKeyHashMap(int initialCapacity,
float loadFactor)
Creates a new, empty map with the specified initial capacity and load
factor and with the default reference types (weak keys, strong values),
and concurrencyLevel (16).
|
ConcurrentWeakKeyHashMap(int initialCapacity,
float loadFactor,
int concurrencyLevel)
Creates a new, empty map with the specified initial capacity, load factor
and concurrency level.
|
ConcurrentWeakKeyHashMap(Map<? extends K,? extends V> m)
Creates a new map with the same mappings as the given map.
|
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Removes all of the mappings from this map.
|
boolean |
contains(Object value)
Legacy method testing if some key maps into the specified value in this
table.
|
boolean |
containsKey(Object key)
Tests if the specified object is a key in this table.
|
boolean |
containsValue(Object value)
Returns true if this map maps one or more keys to the specified
value.
|
Enumeration<V> |
elements()
Returns an enumeration of the values in this table.
|
Set<Map.Entry<K,V>> |
entrySet()
Returns a
Set view of the mappings contained in this map. |
V |
get(Object key)
Returns the value to which the specified key is mapped, or
null
if this map contains no mapping for the key. |
boolean |
isEmpty()
Returns true if this map contains no key-value mappings.
|
Enumeration<K> |
keys()
Returns an enumeration of the keys in this table.
|
Set<K> |
keySet()
Returns a
Set view of the keys contained in this map. |
void |
purgeStaleEntries()
Removes any stale entries whose keys have been finalized.
|
V |
put(K key,
V value)
Maps the specified key to the specified value in this table.
|
void |
putAll(Map<? extends K,? extends V> m)
Copies all of the mappings from the specified map to this one.
|
V |
putIfAbsent(K key,
V value) |
V |
remove(Object key)
Removes the key (and its corresponding value) from this map.
|
boolean |
remove(Object key,
Object value) |
V |
replace(K key,
V value) |
boolean |
replace(K key,
V oldValue,
V newValue) |
int |
size()
Returns the number of key-value mappings in this map.
|
Collection<V> |
values()
Returns a
Collection view of the values contained in this map. |
clone, equals, hashCode, toStringfinalize, getClass, notify, notifyAll, wait, wait, waitcompute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, replaceAllpublic ConcurrentWeakKeyHashMap(int initialCapacity,
float loadFactor,
int concurrencyLevel)
initialCapacity - the initial capacity. The implementation performs
internal sizing to accommodate this many elements.loadFactor - the load factor threshold, used to control resizing.
Resizing may be performed when the average number of
elements per bin exceeds this threshold.concurrencyLevel - the estimated number of concurrently updating
threads. The implementation performs internal
sizing to try to accommodate this many threads.IllegalArgumentException - if the initial capacity is negative or
the load factor or concurrencyLevel are
nonpositive.public ConcurrentWeakKeyHashMap(int initialCapacity,
float loadFactor)
initialCapacity - The implementation performs internal sizing to
accommodate this many elements.loadFactor - the load factor threshold, used to control resizing.
Resizing may be performed when the average number of
elements per bin exceeds this threshold.IllegalArgumentException - if the initial capacity of elements is
negative or the load factor is
nonpositivepublic ConcurrentWeakKeyHashMap(int initialCapacity)
initialCapacity - the initial capacity. The implementation performs
internal sizing to accommodate this many elements.IllegalArgumentException - if the initial capacity of elements is
negative.public ConcurrentWeakKeyHashMap()
public ConcurrentWeakKeyHashMap(Map<? extends K,? extends V> m)
m - the mappublic boolean isEmpty()
public int size()
public V get(Object key)
null
if this map contains no mapping for the key.
More formally, if this map contains a mapping from a key k to
a value v such that key.equals(k), then this method
returns v; otherwise it returns null. (There can be at
most one such mapping.)
get in interface Map<K,V>get in class AbstractMap<K,V>NullPointerException - if the specified key is nullpublic boolean containsKey(Object key)
containsKey in interface Map<K,V>containsKey in class AbstractMap<K,V>key - possible keyNullPointerException - if the specified key is nullpublic boolean containsValue(Object value)
containsValue in interface Map<K,V>containsValue in class AbstractMap<K,V>value - value whose presence in this map is to be testedNullPointerException - if the specified value is nullpublic boolean contains(Object value)
containsValue(java.lang.Object), and exists solely to ensure full compatibility
with class Hashtable, which supported this method prior to
introduction of the Java Collections framework.value - a value to search forNullPointerException - if the specified value is nullpublic V put(K key, V value)
The value can be retrieved by calling the get method with a key that is equal to the original key.
put in interface Map<K,V>put in class AbstractMap<K,V>key - key with which the specified value is to be associatedvalue - value to be associated with the specified keyNullPointerException - if the specified key or value is nullpublic V putIfAbsent(K key, V value)
putIfAbsent in interface ConcurrentMap<K,V>putIfAbsent in interface Map<K,V>NullPointerException - if the specified key or value is nullpublic void putAll(Map<? extends K,? extends V> m)
public V remove(Object key)
remove in interface Map<K,V>remove in class AbstractMap<K,V>key - the key that needs to be removedNullPointerException - if the specified key is nullpublic boolean remove(Object key, Object value)
remove in interface ConcurrentMap<K,V>remove in interface Map<K,V>NullPointerException - if the specified key is nullpublic boolean replace(K key, V oldValue, V newValue)
replace in interface ConcurrentMap<K,V>replace in interface Map<K,V>NullPointerException - if any of the arguments are nullpublic V replace(K key, V value)
replace in interface ConcurrentMap<K,V>replace in interface Map<K,V>NullPointerException - if the specified key or value is nullpublic void clear()
public void purgeStaleEntries()
public Set<K> keySet()
Set view of the keys contained in this map. The set is
backed by the map, so changes to the map are reflected in the set, and
vice-versa. The set supports element removal, which removes the
corresponding mapping from this map, via the Iterator.remove,
Set.remove, removeAll, retainAll, and
clear operations. It does not support the add or
addAll operations.
The view's iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException, and guarantees
to traverse elements as they existed upon construction of the iterator,
and may (but is not guaranteed to) reflect any modifications subsequent
to construction.
public Collection<V> values()
Collection view of the values contained in this map.
The collection is backed by the map, so changes to the map are reflected
in the collection, and vice-versa. The collection supports element
removal, which removes the corresponding mapping from this map, via the
Iterator.remove, Collection.remove, removeAll,
retainAll, and clear operations. It does not support
the add or addAll operations.
The view's iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException, and guarantees
to traverse elements as they existed upon construction of the iterator,
and may (but is not guaranteed to) reflect any modifications subsequent
to construction.
public Set<Map.Entry<K,V>> entrySet()
Set view of the mappings contained in this map.
The set is backed by the map, so changes to the map are reflected in the
set, and vice-versa. The set supports element removal, which removes the
corresponding mapping from the map, via the Iterator.remove,
Set.remove, removeAll, retainAll, and
clear operations. It does not support the add or
addAll operations.
The view's iterator is a "weakly consistent" iterator that
will never throw ConcurrentModificationException, and guarantees
to traverse elements as they existed upon construction of the iterator,
and may (but is not guaranteed to) reflect any modifications subsequent
to construction.
public Enumeration<K> keys()
keySet()public Enumeration<V> elements()
values()Copyright © 2021. All rights reserved.