| java.util.IdentityHashMap
| IdentityHashMap | | public class IdentityHashMap extends AbstractMap implements Map<K, V>,Serializable,Cloneable(Code) | | IdentityHashMap
This is a variant on HashMap which tests equality by reference instead of by
value. Basically, keys and values are compared for equality by checking if
their references are equal rather than by calling the "equals" function.
IdentityHashMap uses open addressing (linear probing in particular) for
collision resolution. This is different from HashMap which uses Chaining.
Like HashMap, IdentityHashMap is not thread safe, so access by multiple
threads must be synchronized by an external mechanism such as
Collections.synchronizedMap.
since:
1.4 |
| Inner Class :static class IdentityHashMapEntry extends MapEntry | |
| Inner Class :static class IdentityHashMapIterator implements Iterator<E> | |
| Inner Class :static class IdentityHashMapEntrySet extends AbstractSet> | |
| Method Summary | |
| public void | clear()
Removes all elements from this Map, leaving it empty. | | public Object | clone()
Answers a new IdentityHashMap with the same mappings and size as this
one. | | public boolean | containsKey(Object key)
Searches this Map for the specified key. | | public boolean | containsValue(Object value)
Searches this Map for the specified value. | | public Set<Map.Entry<K, V>> | entrySet()
Answers a Set of the mappings contained in this IdentityHashMap. | | public boolean | equals(Object object)
Compares this map with other objects. | | public V | get(Object key)
Answers the value of the mapping with the specified key. | | public boolean | isEmpty()
Answers if this IdentityHashMap has no elements, a size of zero. | | public Set<K> | keySet()
Answers a Set of the keys contained in this IdentityHashMap. | | public V | put(K key, V value)
Maps the specified key to the specified value. | | public void | putAll(Map<? extends K, ? extends V> map)
Copies all the mappings in the given map to this map. | | public V | remove(Object key)
Removes a mapping with the specified key from this IdentityHashMap. | | public int | size()
Answers the number of mappings in this IdentityHashMap. | | public Collection<V> | values()
Answers a Collection of the values contained in this IdentityHashMap. |
| modCount | | transient int modCount(Code) | | |
| threshold | | transient int threshold(Code) | | |
| IdentityHashMap | | public IdentityHashMap()(Code) | | Create an IdentityHashMap with default maximum size
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| IdentityHashMap | | public IdentityHashMap(int maxSize)(Code) | | Create an IdentityHashMap with the given maximum size parameter
Parameters:
maxSize - The estimated maximum number of entries that will be put inthis map. |
| IdentityHashMap | | public IdentityHashMap(Map<? extends K, ? extends V> map)(Code) | | Create an IdentityHashMap using the given Map as initial values.
Parameters:
map - A map of (key,value) pairs to copy into the IdentityHashMap |
| clone | | public Object clone()(Code) | | Answers a new IdentityHashMap with the same mappings and size as this
one.
a shallow copy of this IdentityHashMap
See Also: java.lang.Cloneable |
| containsKey | | public boolean containsKey(Object key)(Code) | | Searches this Map for the specified key.
Parameters:
key - the object to search for true if key is a key of this Map, false otherwise |
| containsValue | | public boolean containsValue(Object value)(Code) | | Searches this Map for the specified value.
Parameters:
value - the object to search for true if value is a value of this Map, falseotherwise |
| entrySet | | public Set<Map.Entry<K, V>> entrySet()(Code) | | Answers a Set of the mappings contained in this IdentityHashMap. Each
element in the set is a Map.Entry. The set is backed by this Map so
changes to one are reflected by the other. The set does not support
adding.
a Set of the mappings |
| equals | | public boolean equals(Object object)(Code) | | Compares this map with other objects. This map is equal to another map is
it represents the same set of mappings. With this map, two mappings are
the same if both the key and the value are equal by reference.
When compared with a map that is not an IdentityHashMap, the equals
method is not necessarily symmetric (a.equals(b) implies b.equals(a)) nor
transitive (a.equals(b) and b.equals(c) implies a.equals(c)).
whether the argument object is equal to this object |
| get | | public V get(Object key)(Code) | | Answers the value of the mapping with the specified key.
Parameters:
key - the key the value of the mapping with the specified key |
| isEmpty | | public boolean isEmpty()(Code) | | Answers if this IdentityHashMap has no elements, a size of zero.
true if this IdentityHashMap has no elements, false otherwise
See Also: IdentityHashMap.size |
| keySet | | public Set<K> keySet()(Code) | | Answers a Set of the keys contained in this IdentityHashMap. The set is
backed by this IdentityHashMap so changes to one are reflected by the
other. The set does not support adding.
a Set of the keys |
| put | | public V put(K key, V value)(Code) | | Maps the specified key to the specified value.
Parameters:
key - the key
Parameters:
value - the value the value of any previous mapping with the specified key or nullif there was no mapping |
| putAll | | public void putAll(Map<? extends K, ? extends V> map)(Code) | | Copies all the mappings in the given map to this map. These mappings will
replace all mappings that this map had for any of the keys currently in
the given map.
Parameters:
map - the Map to copy mappings from
throws:
NullPointerException - if the given map is null |
| remove | | public V remove(Object key)(Code) | | Removes a mapping with the specified key from this IdentityHashMap.
Parameters:
key - the key of the mapping to remove the value of the removed mapping, or null if key is not a key inthis Map |
| size | | public int size()(Code) | | Answers the number of mappings in this IdentityHashMap.
the number of mappings in this IdentityHashMap |
| values | | public Collection<V> values()(Code) | | Answers a Collection of the values contained in this IdentityHashMap. The
collection is backed by this IdentityHashMap so changes to one are
reflected by the other. The collection does not support adding.
a Collection of the values |
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