Android
java.util
public class

java.util.IdentityHashMap<K, V>

java.lang.Object
java.util.AbstractMap<K, V> Map<K, V>
java.util.IdentityHashMap<K, V> Serializable Cloneable Map<K, V>

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.

Summary

Public Constructors

            IdentityHashMap()
Create an IdentityHashMap with default maximum size
            IdentityHashMap(int maxSize)
Create an IdentityHashMap with the given maximum size parameter
            IdentityHashMap(Map<? extends K, ? extends V> map)
Create an IdentityHashMap using the given Map as initial values.

Public Methods

          void  clear()
Removes all elements from this Map, leaving it empty.
          Object  clone()
Returns a new IdentityHashMap with the same mappings and size as this one.
          boolean  containsKey(Object key)
Searches this Map for the specified key.
          boolean  containsValue(Object value)
Searches this Map for the specified value.
          Set<Entry<K, V>>  entrySet()
Returns a Set of the mappings contained in this IdentityHashMap.
          boolean  equals(Object object)
Compares this map with other objects.
          get(Object key)
Returns the value of the mapping with the specified key.
          boolean  isEmpty()
Returns if this IdentityHashMap has no elements, a size of zero.
          Set<K>  keySet()
Returns a Set of the keys contained in this IdentityHashMap.
          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.
          remove(Object key)
Removes a mapping with the specified key from this IdentityHashMap.
          int  size()
Returns the number of mappings in this IdentityHashMap.
          Collection<V>  values()
Returns a Collection of the values contained in this IdentityHashMap.
Methods inherited from class java.util.AbstractMap
Methods inherited from class java.lang.Object
Methods inherited from interface java.util.Map

Details

Public Constructors

public IdentityHashMap()

Create an IdentityHashMap with default maximum size

public IdentityHashMap(int maxSize)

Create an IdentityHashMap with the given maximum size parameter

Parameters

maxSize The estimated maximum number of entries that will be put in this map.

public IdentityHashMap(Map<? extends K, ? extends V> map)

Create an IdentityHashMap using the given Map as initial values.

Parameters

map A map of (key,value) pairs to copy into the IdentityHashMap

Public Methods

public void clear()

Removes all elements from this Map, leaving it empty.

Throws

UnsupportedOperationException when removing from this Map is not supported

See Also

public Object clone()

Returns a new IdentityHashMap with the same mappings and size as this one.

Returns

  • a shallow copy of this IdentityHashMap

See Also

public boolean containsKey(Object key)

Searches this Map for the specified key.

Parameters

key the object to search for

Returns

  • true if key is a key of this Map, false otherwise

public boolean containsValue(Object value)

Searches this Map for the specified value.

Parameters

value the object to search for

Returns

  • true if value is a value of this Map, false otherwise

public Set<Entry<K, V>> entrySet()

Returns 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.

Returns

  • a Set of the mappings

public boolean equals(Object object)

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)).

Parameters

object the object to compare with this object

Returns

  • whether the argument object is equal to this object

public V get(Object key)

Returns the value of the mapping with the specified key.

Parameters

key the key

Returns

  • the value of the mapping with the specified key

public boolean isEmpty()

Returns if this IdentityHashMap has no elements, a size of zero.

Returns

  • true if this IdentityHashMap has no elements, false otherwise

See Also

public Set<K> keySet()

Returns 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.

Returns

  • a Set of the keys

public V put(K key, V value)

Maps the specified key to the specified value.

Parameters

key the key
value the value

Returns

  • the value of any previous mapping with the specified key or null if there was no mapping

public void putAll(Map<? extends K, ? extends V> map)

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

public V remove(Object key)

Removes a mapping with the specified key from this IdentityHashMap.

Parameters

key the key of the mapping to remove

Returns

  • the value of the removed mapping, or null if key is not a key in this Map

public int size()

Returns the number of mappings in this IdentityHashMap.

Returns

  • the number of mappings in this IdentityHashMap

public Collection<V> values()

Returns 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.

Returns

  • a Collection of the values
Copyright 2007 Google Inc. Build 0.9_r1-98467 - 14 Aug 2008 18:56