org.modeshape.common.collection

Interface Multimap<K,V>

Type Parameters:

K - the key type

V - the value type

All Known Subinterfaces:

ListMultimap<K,V>

All Known Implementing Classes:

AbstractMultimap, ArrayListMultimap, HashMultimap, LinkedHashMultimap, LinkedListMultimap

public interface Multimap<K,V>

A collection similar to Map, but which may associate multiple values with any single key.

Some implementation may not allow duplicate key-value pairs. In such implementations, calling #pu

Method Summary

Modifier and Type	Method and Description
Map<K,Collection<V>>	asMap() Return a map view that associates each key with the corresponding values in the multimap.
void	clear() Remove all key-value pairs from this multimap.
boolean	containsEntry(Object key, Object value) Determine whether this multimap contains the supplied key-value pair.
boolean	containsKey(K key) Determine whether this multimap associates any values with the supplied key.
boolean	containsValue(Object value) Determine whether this multimap associates at least one key with the supplied value.
Collection<Map.Entry<K,V>>	entries() Return a collection of all key-value pairs.
Collection<V>	get(K key) Get the collection of values that are associated with the supplied key.
boolean	isEmpty()
Set<K>	keySet() Return the set of keys in this multimap.
boolean	put(K key, V value) Associate the supplied value with the given key, returning true if the size of this multimap was increased.
boolean	remove(K key, V value) Remove the supplied key-value pair from this multi-map.
Collection<V>	removeAll(K key) Remove all of the key-value pairs that use the supplied key, returning the collection of values.
int	size() Return the number of key-value pairs in this multimap.
Collection<V>	values() Return a collection of all values in this multimap.

Method Detail

size

int size()

Return the number of key-value pairs in this multimap.

Returns:

the size of this multimap.

isEmpty

boolean isEmpty()

put

boolean put(K key,
            V value)

Associate the supplied value with the given key, returning true if the size of this multimap was increased.

Some implementations allow duplicate key-value pairs, and in these cases this method will always increase the size of the multimap and will thus always return true. Other implementations will not allow duplicate key-value pairs, and may return false if the multimap already contains the supplied key-value pair.

Parameters:

key - the key

value - the value

Returns:

true if the size of this multimap was increased as a result of this call, or false if the multimap already contained the key-value pair and doesn't allow duplicates

remove

boolean remove(K key,
               V value)

Remove the supplied key-value pair from this multi-map.

Parameters:

key - the key

value - the value

Returns:

true if the size of this multimap was decreased as a result of this call, or false if the multimap did not contain the key-value pair

removeAll

Collection<V> removeAll(K key)

Remove all of the key-value pairs that use the supplied key, returning the collection of values. The resulting collection may be modifiable, but changing it will have no effect on this multimap.

Parameters:

key - the key

Returns:

the collection of values that were removed, or an empty collection if there were none; never null

get

Collection<V> get(K key)

Get the collection of values that are associated with the supplied key.

Changes to the returned collection will update the values that this multimap associates with the key.

Parameters:

key - the key

Returns:

the collection of values, or an empty collection if the supplied key was not associated with any values

containsKey

boolean containsKey(K key)

Determine whether this multimap associates any values with the supplied key.

Parameters:

key - the key

Returns:

true if there is at least one value associated with the supplied key, or false otherwise

containsValue

boolean containsValue(Object value)

Determine whether this multimap associates at least one key with the supplied value.

Parameters:

value - the value

Returns:

true if there is at least one key associated with the supplied value, or false otherwise

containsEntry

boolean containsEntry(Object key,
                      Object value)

Determine whether this multimap contains the supplied key-value pair.

Parameters:

key - the key

value - the value

Returns:

true if this multimap contains an entry with the supplied key and value, or false otherwise

keySet

Set<K> keySet()

Return the set of keys in this multimap.

Returns:

the set of keys; never null but possible empty

values

Collection<V> values()

Return a collection of all values in this multimap. Changes to the returned collection will update the underlying multimap, and vice versa.

Returns:

the collection of values, which may include the same value multiple times if it occurs in multiple mappings; never null but possibly empty

entries

Collection<Map.Entry<K,V>> entries()

Return a collection of all key-value pairs. Changes to the returned collection will update the underlying multimap, and vice versa. The entries collection does not support the add or addAll operations.

Returns:

the collection of map entries consisting of key-value pairs; never null but possibly empty

asMap

Map<K,Collection<V>> asMap()

Return a map view that associates each key with the corresponding values in the multimap. Changes to the returned map, such as element removal, will update the underlying multimap. The map does not support setValue() on its entries, put, or putAll.

The collections returned by asMap().get(Object) have the same behavior as those returned by get(K).

Returns:

a map view from a key to its collection of values

clear

void clear()

Remove all key-value pairs from this multimap.