Reference:Java.util.Map

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java.util
public interface java.util.Map

java.util.Map
Map has a set of keys, each key is mapped to a single value.

Contents

[edit] Nested Classes
Map.Entry Map.Entry is a key/value mapping which is contained in a Map.  

[edit] Known Indirect Subclasses

AbstractMap, Attributes, AuthProvider, ConcurrentHashMap, ConcurrentMap, EnumMap, HashMap, Hashtable, IdentityHashMap, LinkedHashMap, Properties, Provider, SortedMap, TreeMap, WeakHashMap

[edit] Summary

[edit] Public Methods

        void  clear ()
Removes all elements from this Map, leaving it empty.
        boolean  containsKey (Object key)
Searches this Map for the specified key.
        boolean  containsValue (Object value)
Searches this Map for the specified value.
        Set   entrySet ()
Returns a Set whose elements comprise all of the mappings that are to be found in this Map.
        boolean  equals (Object object)
Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
        V   get (Object key)
Answers the value of the mapping with the specified key.
        int  hashCode ()
Answers an integer hash code for the receiver.
        boolean  isEmpty ()
Answers if this Map has no elements, a size of zero.
        Set   keySet ()
Answers 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 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 ()
Answers the number of elements in this Map.
        Collection   values ()
Returns all of the current Map values in a Collection.

[edit] Details

[edit] Public Methods

[edit] public void clear()

Removes all elements from this Map, leaving it empty.

Throws

UnsupportedOperationException when removing from this Map is not supported

See Also

[edit] 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

[edit] 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

[edit] public Set entrySet()

Returns a Set whose elements comprise all of the mappings that are to be found in this Map. Information on each of the mappings is encapsulated in a separate Map.Entry instance. As the Set is backed by this Map, users should be aware that changes in one will be immediately visible in the other.

Returns

  • a Set of the mappings

[edit] public boolean equals(Object object)

Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.

Parameters

object 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

[edit] public V get(Object key)

Answers the value of the mapping with the specified key.

Parameters

key the key

Returns

  • the value of the mapping with the specified key

[edit] public int hashCode()

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

Returns

  • the receiver's hash

See Also

[edit] public boolean isEmpty()

Answers if this Map has no elements, a size of zero.

Returns

  • true if this Map has no elements, false otherwise

See Also

[edit] public Set keySet()

Answers a Set of the keys contained in this Map. The set is backed by this Map so changes to one are relected by the other. The set does not support adding.

Returns

  • a Set of the keys

[edit] 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 when adding to this Map is not supported
ClassCastException when the class of the key or value is inappropriate for this Map
IllegalArgumentException when the key or value cannot be added to this Map
NullPointerException when the key or value is null and this Map does not support null keys or values

[edit] public void putAll(Map map)

Copies every mapping in the specified Map to this Map.

Parameters

map the Map to copy mappings from

Throws

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

[edit] 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 key is not a key in this Map

Throws

UnsupportedOperationException when removing from this Map is not supported

[edit] public int size()

Answers the number of elements in this Map.

Returns

  • the number of elements in this Map

[edit] public Collection values()

Returns all of the current Map values in a Collection. As the returned Collection is backed by this Map, users should be aware that changes in one will be immediately visible in the other.

Returns

  • a Collection of the values

[edit] References

Retrieved from "http://wiki.droiddocs.net/Reference:Java.util.Map"
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