public class IdentityHashMap extends AbstractMap implements Map, Cloneable, Serializable
HashMap that uses
System.identityHashCode(Object) for hashing, and reference comparison
instead of Object.equals(Object). Note that this applies only to keys,
and not to values, i.e. containsValue(Object) still uses Object.equals(Object).AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>| Modifier and Type | Field and Description |
|---|---|
static long |
serialVersionUID |
| Constructor and Description |
|---|
IdentityHashMap()
Constructs a new, empty map with a default capacity and load
factor, which is 0.75.
|
IdentityHashMap(int initialCapacity)
Constructs a new, empty map with the specified initial capacity
and default load factor, which is 0.75.
|
IdentityHashMap(int initialCapacity,
float loadFactor)
Constructs a new, empty map with the specified initial
capacity and the specified load factor.
|
IdentityHashMap(Map t)
Constructs a new map with the same mappings as the given map.
|
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Removes all mappings from this map.
|
Object |
clone()
Returns a shallow copy of this IdentityHashMap instance: the keys and
values themselves are not cloned.
|
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 |
entrySet()
Returns a collection view of the mappings contained in this map.
|
Object |
get(Object key)
Returns the value to which this map maps the specified key.
|
boolean |
isEmpty()
Returns true if this map contains no key-value mappings.
|
Set |
keySet()
Returns a set view of the keys contained in this map.
|
Object |
put(Object key,
Object value)
Associates the specified value with the specified key in this map.
|
void |
putAll(Map t)
Copies all of the mappings from the specified map to this one.
|
Object |
remove(Object key)
Removes the mapping for this key from this map if present.
|
int |
size()
Returns the number of key-value mappings in this map.
|
Collection |
values()
Returns a collection view of the values contained in this map.
|
equals, hashCode, toStringfinalize, getClass, notify, notifyAll, wait, wait, waitcompute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAllpublic static final long serialVersionUID
public IdentityHashMap(int initialCapacity,
float loadFactor)
initialCapacity - the initial capacity of the IdentityHashMap.loadFactor - the load factor of the IdentityHashMapIllegalArgumentException - if the initial capacity is less
than zero, or if the load factor is nonpositive.public IdentityHashMap(int initialCapacity)
initialCapacity - the initial capacity of the IdentityHashMap.IllegalArgumentException - if the initial capacity is less
than zero.public IdentityHashMap()
public IdentityHashMap(Map t)
t - the map whose mappings are to be placed in this map.public int size()
size in interface Mapsize in class AbstractMappublic boolean isEmpty()
isEmpty in interface MapisEmpty in class AbstractMappublic boolean containsValue(Object value)
containsValue in interface MapcontainsValue in class AbstractMapvalue - value whose presence in this map is to be tested.public boolean containsKey(Object key)
containsKey in interface MapcontainsKey in class AbstractMapkey - key whose presence in this Map is to be tested.public Object get(Object key)
get in interface Mapget in class AbstractMapkey - key whose associated value is to be returned.public Object put(Object key, Object value)
put in interface Mapput in class AbstractMapkey - key with which the specified value is to be associated.value - value to be associated with the specified key.public Object remove(Object key)
remove in interface Mapremove in class AbstractMapkey - key whose mapping is to be removed from the map.public void putAll(Map t)
putAll in interface MapputAll in class AbstractMapt - Mappings to be stored in this map.public void clear()
clear in interface Mapclear in class AbstractMappublic Object clone()
clone in class AbstractMappublic Set keySet()
keySet in interface MapkeySet in class AbstractMappublic Collection values()
values in interface Mapvalues in class AbstractMappublic Set entrySet()
entrySet in interface MapentrySet in class AbstractMapMap.Entry