java.util.HashMap< K, V > Class Template Reference

Inheritance diagram for java.util.HashMap< K, V >:

Classes
class	Entry
class	HashMapEntrySet

Public Member Functions
	HashMap ()
	HashMap (int capacity)
	HashMap (int capacity, float loadFactor)
	HashMap (Map<? extends K, ? extends V > map)
void	clear ()
Object	clone ()
boolean	containsKey (Object key)
boolean	containsValue (Object value)
Set< Map.Entry< K, V > >	entrySet ()
V	get (Object key)
boolean	isEmpty ()
Set< K >	keySet ()
V	put (K key, V value)
void	putAll (Map<? extends K, ? extends V > map)
V	remove (Object key)
int	size ()
Collection< V >	values ()
Public Member Functions inherited from java.util.AbstractMap< K, V >
void	clear ()
boolean	containsKey (Object key)
boolean	containsValue (Object value)
abstract Set< Map.Entry< K, V > >	entrySet ()
boolean	equals (Object object)
V	get (Object key)
int	hashCode ()
boolean	isEmpty ()
Set< K >	keySet ()
V	put (K key, V value)
void	putAll (Map<? extends K, ? extends V > map)
V	remove (Object key)
int	size ()
String	toString ()
Collection< V >	values ()
Public Member Functions inherited from java.util.Map< K, V >
void	putAll (Map<? extends K,? extends V > map)

Additional Inherited Members
Protected Member Functions inherited from java.util.AbstractMap< K, V >
Object	clone () throws CloneNotSupportedException

Detailed Description

HashMap is an implementation of Map. All optional operations (adding and removing) are supported. Keys and values can be any objects.

Constructor & Destructor Documentation

HashMap() [1/4]

java.util.HashMap< K, V >.HashMap ( )

inline

Constructs a new empty

HashMap 

instance.

HashMap() [2/4]

java.util.HashMap< K, V >.HashMap ( int  capacity )

inline

Constructs a new

HashMap 

instance with the specified capacity.

Parameters

capacity

the initial capacity of this hash map.

Exceptions

IllegalArgumentException

when the capacity is less than zero.

HashMap() [3/4]

java.util.HashMap< K, V >.HashMap ( int  capacity, float  loadFactor  )

inline

Constructs a new

HashMap 

instance with the specified capacity and load factor.

Parameters

capacity	the initial capacity of this hash map.
loadFactor	the initial load factor.

Exceptions

IllegalArgumentException

when the capacity is less than zero or the load factor is less or equal to zero.

HashMap() [4/4]

java.util.HashMap< K, V >.HashMap ( Map<? extends K, ? extends V >  map )

inline

Constructs a new

HashMap 

instance containing the mappings from the specified map.

Parameters

map	the mappings to add.

Member Function Documentation

clear()

void java.util.HashMap< K, V >.clear ( )

inline

Removes all mappings from this hash map, leaving it empty.

See also

isEmpty

size

Implements java.util.Map< K, V >.

clone()

Object java.util.HashMap< K, V >.clone ( )

inline

Returns a shallow copy of this map.

Returns

a shallow copy of this map.

containsKey()

boolean java.util.HashMap< K, V >.containsKey ( Object  key )

inline

Returns whether this map contains the specified key.

Parameters

key	the key to search for.

Returns

true 

if this map contains the specified key,

false 

otherwise.

Implements java.util.Map< K, V >.

containsValue()

boolean java.util.HashMap< K, V >.containsValue ( Object  value )

inline

Returns whether this map contains the specified value.

Parameters

value

the value to search for.

Returns

true 

if this map contains the specified value,

false 

otherwise.

Implements java.util.Map< K, V >.

entrySet()

Set<Map.Entry<K, V> > java.util.HashMap< K, V >.entrySet ( )

inline

Returns a set containing all of the mappings in this map. Each mapping is an instance of Map.Entry. As the set is backed by this map, changes in one will be reflected in the other.

Returns

a set of the mappings.

Implements java.util.Map< K, V >.

get()

V java.util.HashMap< K, V >.get ( Object  key )

inline

Returns the value of the mapping with the specified key.

Parameters

key

the key.

Returns

the value of the mapping with the specified key, or

null 

if no mapping for the specified key is found.

Implements java.util.Map< K, V >.

isEmpty()

boolean java.util.HashMap< K, V >.isEmpty ( )

inline

Returns whether this map is empty.

Returns

true 

if this map has no elements,

false 

otherwise.

See also

size()

Implements java.util.Map< K, V >.

keySet()

Set<K> java.util.HashMap< K, V >.keySet ( )

inline

Returns a set of the keys contained in this map. 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 keys.

Implements java.util.Map< K, V >.

put()

V java.util.HashMap< K, V >.put ( K  key, V  value  )

inline

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 such mapping.

Implements java.util.Map< K, V >.

putAll()

void java.util.HashMap< K, V >.putAll ( Map<? extends K, ? extends V >  map )

inline

Copies all the mappings in the specified 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.

Exceptions

NullPointerException

if map is null .

remove()

V java.util.HashMap< K, V >.remove ( Object  key )

inline

Removes the mapping with the specified key from this map.

Parameters

key	the key of the mapping to remove.

Returns

the value of the removed mapping or

null 

if no mapping for the specified key was found.

Implements java.util.Map< K, V >.

size()

int java.util.HashMap< K, V >.size ( )

inline

Returns the number of elements in this map.

Returns

the number of elements in this map.

Implements java.util.Map< K, V >.

values()

Collection<V> java.util.HashMap< K, V >.values ( )

inline

Returns a collection of the values contained in this map. The collection is backed by this map so changes to one are reflected by the other. The collection supports remove, removeAll, retainAll and clear operations, and it does not support add or addAll operations.

This method returns a collection which is the subclass of AbstractCollection. The iterator method of this subclass returns a "wrapper object" over the iterator of map's entrySet(). The

size 

method wraps the map's size method and the

contains 

method wraps the map's containsValue method.

The collection is created when this method is called for the first time and returned in response to all subsequent calls. This method may return different collections when multiple concurrent calls occur, since no synchronization is performed.

Returns

a collection of the values contained in this map.

Implements java.util.Map< K, V >.

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The documentation for this class was generated from the following file:

• src/java/util/HashMap.java