Summary: Nested Classes | Protected Ctors | Methods | Inherited Methods | [Expand All]

public abstract class

AbstractMap

extends Object
implements Map<K, V>

java.lang.Object
↳	java.util.AbstractMap<K, V>

Known Direct Subclasses

HashMap<K, V>, TreeMap<K, V>

Known Indirect Subclasses

LinkedHashMap<K, V>

Class Overview

This class is an abstract implementation of the Map interface. This implementation does not support adding. A subclass must implement the abstract method entrySet().

Summary

Nested Classes
class	AbstractMap.SimpleEntry<K, V>	A key-value mapping.
class	AbstractMap.SimpleImmutableEntry<K, V>	An immutable key-value mapping.

Protected Constructors
	AbstractMap() Constructs a new instance of this `AbstractMap`.

Public Methods
void	clear() Removes all elements from this map, leaving it empty.
boolean	containsKey(Object key) Returns whether this map contains the specified key.
boolean	containsValue(Object value) Returns whether this map contains the specified value.
abstract Set<Entry<K, V>>	entrySet() Returns a set containing all of the mappings in this map.
boolean	equals(Object object) Compares the specified object to this instance, and returns `true` if the specified object is a map and both maps contain the same mappings.
V	get(Object key) Returns the value of the mapping with the specified key.
int	hashCode() Returns the hash code for this object.
boolean	isEmpty() Returns whether this map is empty.
Set<K>	keySet() Returns a set of the keys contained in this map.
V	put(K key, V value) Maps the specified key to the specified value.
void	putAll(Map<? extends K, ? extends V> map) Copies every mapping in the specified map to this map.
V	remove(Object key) Removes a mapping with the specified key from this Map.
int	size() Returns the number of elements in this map.
String	toString() Returns the string representation of this map.
Collection<V>	values() Returns a collection of the values contained in this map.

[Expand]

Inherited Methods

From class java.lang.Object

boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
final Class<?>	getClass() Returns the runtime class of an object.
int	hashCode() Returns a hash code value for the object.
final void	notify() Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll() Wakes up all threads that are waiting on this object's monitor.
String	toString() Returns a string representation of the object.
final void	wait(long timeout, int nanos) Causes current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void	wait(long timeout) Causes current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
final void	wait() Causes current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

From interface java.util.Map

abstract void	clear() Removes all elements from this `Map`, leaving it empty.
abstract boolean	containsKey(Object key) Returns whether this `Map` contains the specified key.
abstract boolean	containsValue(Object value) Returns whether this `Map` contains the specified value.
abstract Set<Entry<K, V>>	entrySet() Returns a `Set` containing all of the mappings in this `Map`.
abstract boolean	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.
abstract V	get(Object key) Returns the value of the mapping with the specified key.
abstract int	hashCode() Returns an integer hash code for the receiver.
abstract boolean	isEmpty() Returns whether this map is empty.
abstract Set<K>	keySet() Returns a set of the keys contained in this `Map`.
abstract V	put(K key, V value) Maps the specified key to the specified value.
abstract void	putAll(Map<? extends K, ? extends V> map) Copies every mapping in the specified `Map` to this `Map`.
abstract V	remove(Object key) Removes a mapping with the specified key from this `Map`.
abstract int	size() Returns the number of mappings in this `Map`.
abstract Collection<V>	values() Returns a `Collection` of the values contained in this `Map`.

Protected Constructors

protected AbstractMap ()

Constructs a new instance of this AbstractMap.

Public Methods

public void clear ()

Removes all elements from this map, leaving it empty.

Throws

UnsupportedOperationException	if removing from this map is not supported.

public boolean 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.

public boolean 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.

public abstract Set<Entry<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.

public boolean equals (Object object)

Compares the specified object to this instance, and returns true if the specified object is a map and both maps 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, and false if it is different from 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, or null if no mapping for the specified key is found.

public int hashCode ()

Returns the hash code for this object. Objects which are equal must return the same value for this method.

Returns

the hash code of this object.

public boolean isEmpty ()

Returns whether this map is empty.

Returns

true if this map has no elements, false otherwise.

public Set<K> 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 returned 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.

Throws

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.

public void 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.

Throws

UnsupportedOperationException	if adding to this map is not supported.
ClassCastException	if the class of a key or value 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.

public 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.

Throws

UnsupportedOperationException	if removing from this map is not supported.

public int size ()

Returns the number of elements in this map.

Returns

the number of elements in this map.

public String toString ()

Returns the string representation of this map.

Returns

the string representation of this map.

public Collection<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 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 to this method, since no synchronization is performed.

Returns

a collection of the values contained in this map.

Interfaces

Classes

Exceptions

AbstractMap

Class Overview

Summary

Protected Constructors

protected AbstractMap ()

Public Methods

public void clear ()

Throws

See Also

public boolean containsKey (Object key)

Parameters

Returns

public boolean containsValue (Object value)

Parameters

Returns

public abstract Set<Entry<K, V>> entrySet ()

Returns

public boolean equals (Object object)

Parameters

Returns

See Also

public V get (Object key)

Parameters

Returns

public int hashCode ()

Returns

See Also

public boolean isEmpty ()

Returns

See Also

public Set<K> keySet ()

Returns

public V put (K key, V value)

Parameters

Returns

Throws

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

Parameters

Throws

public V remove (Object key)

Parameters

Returns

Throws

public int size ()

Returns

public String toString ()

Returns

public Collection<V> values ()

Returns