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

Classes
interface	Entry

Public Member Functions
void	clear ()

boolean	containsKey (Object key)

boolean	containsValue (Object value)

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 ()

Collection< V >	values ()

Detailed Description

A

Map

is a data structure consisting of a set of keys and values in which each key is mapped to a single value. The class of the objects used as keys is declared when the

Map

is declared, as is the class of the corresponding values.

A

Map

provides helper methods to iterate through all of the keys contained in it, as well as various methods to access and update the key/value pairs.

Member Function Documentation

◆ clear()

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

Removes all elements from this

Map

, leaving it empty.

Exceptions

UnsupportedOperationException

if removing elements from this

Map

is not supported.

See also: isEmpty(); size()

Implemented in java.util.LinkedHashMap< K, V >, java.util.Hashtable< K, V >, java.util.HashMap< K, V >, and java.util.AbstractMap< K, V >.

◆ containsKey()

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

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.

Implemented in java.util.HashMap< K, V >, java.util.Hashtable< K, V >, and java.util.AbstractMap< K, V >.

◆ containsValue()

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

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.

Implemented in java.util.HashMap< K, V >, java.util.Hashtable< K, V >, java.util.LinkedHashMap< K, V >, and java.util.AbstractMap< K, V >.

◆ entrySet()

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

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

Implemented in java.util.Hashtable< K, V >, java.util.LinkedHashMap< K, V >, java.util.HashMap< K, V >, and java.util.AbstractMap< K, V >.

◆ equals()

boolean java.util.Map< K, V >.equals ( Object object )

Compares the argument to the receiver, and returns

true

if the specified object is a

Map

and both

Map

s contain the same mappings.

Parameters

object

the

Object

to compare with this

Object

.

Returns: boolean
true
if the
Object
is the same as this
Object

false
if it is different from this
Object
.

See also: hashCode(); entrySet()

Implemented in java.util.Hashtable< K, V >, and java.util.AbstractMap< K, V >.

◆ get()

V java.util.Map< K, 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, or
null
if no mapping for the specified key is found.

Implemented in java.util.HashMap< K, V >, java.util.LinkedHashMap< K, V >, java.util.AbstractMap< K, V >, and java.util.Hashtable< K, V >.

◆ hashCode()

int java.util.Map< K, V >.hashCode ( )

Returns an integer hash code for the receiver.

Object

s which are equal return the same value for this method.

Returns: the receiver's hash.

See also: equals(Object)

Implemented in java.util.Hashtable< K, V >, and java.util.AbstractMap< K, V >.

◆ isEmpty()

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

Returns whether this map is empty.

Returns: true
if this map has no elements,
false
otherwise.

See also: size()

Implemented in java.util.HashMap< K, V >, java.util.AbstractMap< K, V >, and java.util.Hashtable< K, V >.

◆ keySet()

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

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.

Implemented in java.util.Hashtable< K, V >, java.util.HashMap< K, V >, java.util.LinkedHashMap< K, V >, and java.util.AbstractMap< K, V >.

◆ put()

V java.util.Map< K, 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.

Exceptions

UnsupportedOperationException	if adding to this Map is not supported.
ClassCastException	if the class of the key or value is inappropriate for this Map .
IllegalArgumentException	if the key or value cannot be added to this Map .
NullPointerException	if the key or value is null and this Map does not support null keys or values.

Implemented in java.util.HashMap< K, V >, java.util.AbstractMap< K, V >, java.util.Hashtable< K, V >, and java.util.LinkedHashMap< K, V >.

◆ putAll()

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

Copies every mapping in the specified

Map

to this

Map

.

Parameters

map	the Map to copy mappings from.

Exceptions

UnsupportedOperationException	if adding to this Map is not supported.
ClassCastException	if the class of a key or a value of the specified Map is inappropriate for this Map .
IllegalArgumentException	if a key or value cannot be added to this Map .
NullPointerException	if a key or value is null and this Map does not support null keys or values.

◆ remove()

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

Removes a 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.

Exceptions

UnsupportedOperationException

if removing from this

Map

is not supported.

Implemented in java.util.HashMap< K, V >, java.util.LinkedHashMap< K, V >, java.util.Hashtable< K, V >, and java.util.AbstractMap< K, V >.

◆ size()

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

Returns the number of mappings in this

Map

.

Returns: the number of mappings in this
Map
.

Implemented in java.util.HashMap< K, V >, java.util.AbstractMap< K, V >, and java.util.Hashtable< K, V >.

◆ values()

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

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 Collection#remove, Collection#removeAll, Collection#retainAll, and Collection#clear operations, and it does not support Collection#add or Collection#addAll operations.

This method returns a

Collection

which is the subclass of AbstractCollection. The AbstractCollection#iterator method of this subclass returns a "wrapper object" over the iterator of this

Map

's entrySet(). The AbstractCollection#size method wraps this

Map

's size method and the AbstractCollection#contains method wraps this

Map

's containsValue method.

The collection is created when this method is called at first time and returned in response to all subsequent calls. This method may return different Collection when multiple calls to this method, since it has no synchronization performed.

Returns: a collection of the values contained in this map.

Implemented in java.util.HashMap< K, V >, java.util.Hashtable< K, V >, java.util.LinkedHashMap< K, V >, and java.util.AbstractMap< K, V >.

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

src/java/util/Map.java

Classes

Public Member Functions

Detailed Description

Member Function Documentation

◆ clear()

◆ containsKey()

◆ containsValue()

◆ entrySet()

◆ equals()

◆ get()

◆ hashCode()

◆ isEmpty()

◆ keySet()

◆ put()

◆ putAll()

◆ remove()

◆ size()

◆ values()