public class WeakIdentityHashMap<K,V> extends AbstractMap<K,V> implements Map<K,V>
OpenJDK / jdk8u / jdk8u-dev / jdk
src/share/classes/java/util/WeakHashMap.java @ 13329:c35f231af17a
with the following changes:
WeakHashMap to WeakIdentityHashMap
in the code (but not the JavaDoc! So the diff is easier to read.).import statements.WeakIdentityHashMap.keySet and WeakIdentityHashMap.values
from AbstractMap, which are otherwise package-private.WeakIdentityHashMap.hash(Object) to use System.identityHashCode(Object).WeakIdentityHashMap.eq(Object, Object) to compare objects with reference equality.Entry#hashCode() to use System.identityHashCode(Object)
to contribute to the hash code of an Entry.Entry#equals(Object) to compare keys using reference equality
(after which the values are compared with Object.equals(Object)).AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>| Constructor and Description |
|---|
WeakIdentityHashMap()
Constructs a new, empty WeakHashMap with the default initial
capacity (16) and load factor (0.75).
|
WeakIdentityHashMap(int initialCapacity)
Constructs a new, empty WeakHashMap with the given initial
capacity and the default load factor (0.75).
|
WeakIdentityHashMap(int initialCapacity,
float loadFactor)
Constructs a new, empty WeakHashMap with the given initial
capacity and the given load factor.
|
WeakIdentityHashMap(Map<? extends K,? extends V> m)
Constructs a new WeakHashMap with the same mappings as the
specified map.
|
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Removes all of the mappings from this map.
|
boolean |
containsKey(Object key)
Returns true if this map contains a mapping for the
specified key.
|
boolean |
containsValue(Object value)
Returns true if this map maps one or more keys to the
specified value.
|
Set<Map.Entry<K,V>> |
entrySet()
Returns a
Set view of the mappings contained in this map. |
void |
forEach(BiConsumer<? super K,? super V> action) |
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.
|
Set<K> |
keySet()
Returns a
Set view of the keys contained in this map. |
V |
put(K key,
V value)
Associates the specified value with the specified key in this map.
|
void |
putAll(Map<? extends K,? extends V> m)
Copies all of the mappings from the specified map to this map.
|
V |
remove(Object key)
Removes the mapping for a key from this weak hash map if it is present.
|
void |
replaceAll(BiFunction<? super K,? super V,? extends V> function) |
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, equals, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replacepublic WeakIdentityHashMap(int initialCapacity,
float loadFactor)
initialCapacity - The initial capacity of the WeakHashMaploadFactor - The load factor of the WeakHashMapIllegalArgumentException - if the initial capacity is negative,
or if the load factor is nonpositive.public WeakIdentityHashMap(int initialCapacity)
initialCapacity - The initial capacity of the WeakHashMapIllegalArgumentException - if the initial capacity is negativepublic WeakIdentityHashMap()
public WeakIdentityHashMap(Map<? extends K,? extends V> m)
m - the map whose mappings are to be placed in this mapNullPointerException - if the specified map is nullpublic int size()
public boolean isEmpty()
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==null ? k==null :
key.equals(k)), then this method returns v; otherwise
it returns null. (There can be at most one such mapping.)
A return value of null does not necessarily
indicate that the map contains no mapping for the key; it's also
possible that the map explicitly maps the key to null.
The containsKey operation may be used to
distinguish these two cases.
get in interface Map<K,V>get in class AbstractMap<K,V>WeakIdentityHashMap.put(Object, Object)public boolean containsKey(Object key)
containsKey in interface Map<K,V>containsKey in class AbstractMap<K,V>key - The key whose presence in this map is to be testedpublic V put(K key, V value)
put in interface Map<K,V>put in class AbstractMap<K,V>key - key with which the specified value is to be associated.value - value to be associated with the specified key.public void putAll(Map<? extends K,? extends V> m)
putAll in interface Map<K,V>putAll in class AbstractMap<K,V>m - mappings to be stored in this map.NullPointerException - if the specified map is null.public V remove(Object key)
(key==null ? k==null :
key.equals(k)), that mapping is removed. (The map can contain
at most one such mapping.)
Returns the value to which this map previously associated the key, or null if the map contained no mapping for the key. A return value of null does not necessarily indicate that the map contained no mapping for the key; it's also possible that the map explicitly mapped the key to null.
The map will not contain a mapping for the specified key once the call returns.
public void clear()
public 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 testedpublic 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. If the map is modified
while an iteration over the set is in progress (except through
the iterator's own remove operation), the results of
the iteration are undefined. 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.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. If the map is
modified while an iteration over the collection is in progress
(except through the iterator's own remove operation),
the results of the iteration are undefined. The collection
supports element removal, which removes the corresponding
mapping from the map, via the Iterator.remove,
Collection.remove, removeAll,
retainAll and clear operations. It does not
support the add or addAll operations.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. If the map is modified
while an iteration over the set is in progress (except through
the iterator's own remove operation, or through the
setValue operation on a map entry returned by the
iterator) the results of the iteration are undefined. 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.public void forEach(BiConsumer<? super K,? super V> action)
public void replaceAll(BiFunction<? super K,? super V,? extends V> function)
replaceAll in interface Map<K,V>