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Summary: Nested Classes | Methods | [Expand All]

Added in API level 1

public interface

Map

java.util.Map<K, V>

Known Indirect Subclasses

AbstractMap<K, V>, ArrayMap<K, V>, Attributes, AuthProvider, ConcurrentHashMap<K, V>, ConcurrentMap<K, V>, ConcurrentNavigableMap<K, V>, ConcurrentSkipListMap<K, V>, EnumMap<K extends Enum<K>, V>, HashMap<K, V>, Hashtable<K, V>, IdentityHashMap<K, V>, LinkedHashMap<K, V>, and 6 others.

AbstractMap<K, V>	A base class for `Map` implementations.
ArrayMap<K, V>	ArrayMap is a generic key->value mapping data structure that is designed to be more memory efficient than a traditional `HashMap`.
Attributes	The `Attributes` class is used to store values for manifest entries.
AuthProvider	Legacy security code; do not use.
ConcurrentHashMap<K, V>	A hash table supporting full concurrency of retrievals and high expected concurrency for updates.
ConcurrentMap<K, V>	A `Map` providing additional atomic `putIfAbsent`, `remove`, and `replace` methods.
ConcurrentNavigableMap<K, V>	A `ConcurrentMap` supporting `NavigableMap` operations, and recursively so for its navigable sub-maps.
ConcurrentSkipListMap<K, V>	A scalable concurrent `ConcurrentNavigableMap` implementation.
EnumMap<K extends Enum<K>, V>	An `Map` specialized for use with `Enum` types as keys.
HashMap<K, V>	HashMap is an implementation of `Map`.
Hashtable<K, V>	Hashtable is a synchronized implementation of `Map`.
IdentityHashMap<K, V>	IdentityHashMap is a variant on HashMap which tests equality by reference instead of equality by value.
LinkedHashMap<K, V>	LinkedHashMap is an implementation of `Map` that guarantees iteration order.
NavigableMap<K, V>	A `SortedMap` extended with navigation methods returning the closest matches for given search targets.
ObservableArrayMap<K, V>
ObservableMap<K, V>	A `Map` that notifies when items change.
Properties	A `Properties` object is a `Hashtable` where the keys and values must be `String`s.
Provider	`Provider` is the abstract superclass for all security providers in the Java security infrastructure.
SortedMap<K, V>	A map that has its keys ordered.
TreeMap<K, V>	A map whose entries are sorted by their keys.
WeakHashMap<K, V>	WeakHashMap is an implementation of Map with keys which are WeakReferences.

Class Overview

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.

Summary

Nested Classes
interface	Map.Entry<K, V>	`Map.Entry` is a key/value mapping contained in a `Map`.

Public Methods
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`.

Public Methods

public abstract void clear ()

Added in API level 1

Removes all elements from this Map, leaving it empty.

Throws

UnsupportedOperationException	if removing elements from this `Map` is not supported.

public abstract boolean containsKey (Object key)

Added in API level 1

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 abstract boolean containsValue (Object value)

Added in API level 1

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 ()

Added in API level 1

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 abstract boolean equals (Object object)

Added in API level 1

Compares the argument to the receiver, 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 false if it is different from this Object.

public abstract V get (Object key)

Added in API level 1

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 abstract int hashCode ()

Added in API level 1

Returns an integer hash code for the receiver. Objects which are equal return the same value for this method.

Returns

the receiver's hash.

public abstract boolean isEmpty ()

Added in API level 1

Returns whether this map is empty.

Returns

true if this map has no elements, false otherwise.

public abstract Set<K> keySet ()

Added in API level 1

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.

public abstract V put (K key, V value)

Added in API level 1

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

Added in API level 1

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 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.

public abstract V remove (Object key)

Added in API level 1

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 abstract int size ()

Added in API level 1

Returns the number of mappings in this Map.

Returns

the number of mappings in this Map.

public abstract Collection<V> values ()

Added in API level 1

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(Object), removeAll(Collection), retainAll(Collection), and clear() operations, and it does not support add(E) or addAll(Collection) 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 this Map's entrySet(). The size() method wraps this Map's size() method and the contains(Object) method wraps this Map's containsValue(Object) 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.

Results

Interfaces

Classes

Enums

Exceptions

Errors

Map

Class Overview

Summary

Public Methods

public abstract void clear ()

Throws

See Also

public abstract boolean containsKey (Object key)

Parameters

Returns

public abstract boolean containsValue (Object value)

Parameters

Returns

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

Returns

public abstract boolean equals (Object object)

Parameters

Returns

See Also

public abstract V get (Object key)

Parameters

Returns

public abstract int hashCode ()

Returns

See Also

public abstract boolean isEmpty ()

Returns

See Also

public abstract Set<K> keySet ()

Returns

public abstract V put (K key, V value)

Parameters

Returns

Throws

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

Parameters

Throws

public abstract V remove (Object key)

Parameters

Returns

Throws

public abstract int size ()

Returns

public abstract Collection<V> values ()

Returns