com.google.common.collect
Class ForwardingMultimap<K,V>

java.lang.Object
  com.google.common.collect.ForwardingObject
      com.google.common.collect.ForwardingMultimap<K,V>

All Implemented Interfaces:

Multimap<K,V>

Direct Known Subclasses:

ForwardingListMultimap, ForwardingSetMultimap

@GwtCompatible
public abstract class ForwardingMultimap<K,V>
extends ForwardingObject
implements Multimap<K,V>

A multimap which forwards all its method calls to another multimap. Subclasses should override one or more methods to modify the behavior of the backing multimap as desired per the decorator pattern.

Since:

2.0 (imported from Google Collections Library)

Author:

Robert Konigsberg

Constructor Summary

protected

ForwardingMultimap() Constructor for use by subclasses.

Method Summary

Map<K,Collection<V>>	asMap() Returns a map view that associates each key with the corresponding values in the multimap.
void	clear() Removes all key-value pairs from the multimap.
boolean	containsEntry(Object key, Object value) Returns true if the multimap contains the specified key-value pair.
boolean	containsKey(Object key) Returns true if the multimap contains any values for the specified key.
boolean	containsValue(Object value) Returns true if the multimap contains the specified value for any key.
protected abstract Multimap<K,V>	delegate() Returns the backing delegate instance that methods are forwarded to.
Collection<Map.Entry<K,V>>	entries() Returns a collection of all key-value pairs.
boolean	equals(Object object) Compares the specified object with this multimap for equality.
Collection<V>	get(K key) Returns a collection view of all values associated with a key.
int	hashCode() Returns the hash code for this multimap.
boolean	isEmpty() Returns true if the multimap contains no key-value pairs.
Multiset<K>	keys() Returns a collection, which may contain duplicates, of all keys.
Set<K>	keySet() Returns the set of all keys, each appearing once in the returned set.
boolean	put(K key, V value) Stores a key-value pair in the multimap.
boolean	putAll(K key, Iterable<? extends V> values) Stores a collection of values with the same key.
boolean	putAll(Multimap<? extends K,? extends V> multimap) Copies all of another multimap's key-value pairs into this multimap.
boolean	remove(Object key, Object value) Removes a key-value pair from the multimap.
Collection<V>	removeAll(Object key) Removes all values associated with a given key.
Collection<V>	replaceValues(K key, Iterable<? extends V> values) Stores a collection of values with the same key, replacing any existing values for that key.
int	size() Returns the number of key-value pairs in the multimap.
Collection<V>	values() Returns a collection of all values in the multimap.

Methods inherited from class com.google.common.collect.ForwardingObject

toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ForwardingMultimap

protected ForwardingMultimap()

Constructor for use by subclasses.

Method Detail

delegate

protected abstract Multimap<K,V> delegate()

Description copied from class: ForwardingObject

Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such as ForwardingSet.delegate(). Concrete subclasses override this method to supply the instance being decorated.

Specified by:

delegate in class ForwardingObject

asMap

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

Description copied from interface: Multimap

Returns 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.

When passed a key that is present in the map, asMap().get(Object) has the same behavior as Multimap.get(K), returning a live collection. When passed a key that is not present, however, asMap().get(Object) returns null instead of an empty collection.

Specified by:

asMap in interface Multimap<K,V>

Returns:

a map view from a key to its collection of values

clear

public void clear()

Description copied from interface: Multimap

Removes all key-value pairs from the multimap.

Specified by:

clear in interface Multimap<K,V>

containsEntry

public boolean containsEntry(@Nullable
                             Object key,
                             @Nullable
                             Object value)

Description copied from interface: Multimap

Returns true if the multimap contains the specified key-value pair.

Specified by:

containsEntry in interface Multimap<K,V>

Parameters:

key - key to search for in multimap

value - value to search for in multimap

containsKey

public boolean containsKey(@Nullable
                           Object key)

Description copied from interface: Multimap

Returns true if the multimap contains any values for the specified key.

Specified by:

containsKey in interface Multimap<K,V>

Parameters:

key - key to search for in multimap

containsValue

public boolean containsValue(@Nullable
                             Object value)

Description copied from interface: Multimap

Returns true if the multimap contains the specified value for any key.

Specified by:

containsValue in interface Multimap<K,V>

Parameters:

value - value to search for in multimap

entries

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

Description copied from interface: Multimap

Returns 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.

Specified by:

entries in interface Multimap<K,V>

Returns:

collection of map entries consisting of key-value pairs

get

public Collection<V> get(@Nullable
                         K key)

Description copied from interface: Multimap

Returns a collection view of all values associated with a key. If no mappings in the multimap have the provided key, an empty collection is returned.

Changes to the returned collection will update the underlying multimap, and vice versa.

Specified by:

get in interface Multimap<K,V>

Parameters:

key - key to search for in multimap

Returns:

the collection of values that the key maps to

isEmpty

public boolean isEmpty()

Description copied from interface: Multimap

Returns true if the multimap contains no key-value pairs.

Specified by:

isEmpty in interface Multimap<K,V>

keys

public Multiset<K> keys()

Description copied from interface: Multimap

Returns a collection, which may contain duplicates, of all keys. The number of times of key appears in the returned multiset equals the number of mappings the key has in the multimap. Changes to the returned multiset will update the underlying multimap, and vice versa.

Specified by:

keys in interface Multimap<K,V>

Returns:

a multiset with keys corresponding to the distinct keys of the multimap and frequencies corresponding to the number of values that each key maps to

keySet

public Set<K> keySet()

Description copied from interface: Multimap

Returns the set of all keys, each appearing once in the returned set. Changes to the returned set will update the underlying multimap, and vice versa.

Specified by:

keySet in interface Multimap<K,V>

Returns:

the collection of distinct keys

put

public boolean put(K key,
                   V value)

Description copied from interface: Multimap

Stores a key-value pair in the multimap.

Some multimap implementations allow duplicate key-value pairs, in which case put always adds a new key-value pair and increases the multimap size by 1. Other implementations prohibit duplicates, and storing a key-value pair that's already in the multimap has no effect.

Specified by:

put in interface Multimap<K,V>

Parameters:

key - key to store in the multimap

value - value to store in the multimap

Returns:

true if the method increased the size of the multimap, or false if the multimap already contained the key-value pair and doesn't allow duplicates

putAll

public boolean putAll(K key,
                      Iterable<? extends V> values)

Description copied from interface: Multimap

Stores a collection of values with the same key.

Specified by:

putAll in interface Multimap<K,V>

Parameters:

key - key to store in the multimap

values - values to store in the multimap

Returns:

true if the multimap changed

putAll

public boolean putAll(Multimap<? extends K,? extends V> multimap)

Description copied from interface: Multimap

Copies all of another multimap's key-value pairs into this multimap. The order in which the mappings are added is determined by multimap.entries().

Specified by:

putAll in interface Multimap<K,V>

Parameters:

multimap - mappings to store in this multimap

Returns:

true if the multimap changed

remove

public boolean remove(@Nullable
                      Object key,
                      @Nullable
                      Object value)

Description copied from interface: Multimap

Removes a key-value pair from the multimap.

Specified by:

remove in interface Multimap<K,V>

Parameters:

key - key of entry to remove from the multimap

value - value of entry to remove the multimap

Returns:

true if the multimap changed

removeAll

public Collection<V> removeAll(@Nullable
                               Object key)

Description copied from interface: Multimap

Removes all values associated with a given key.

Specified by:

removeAll in interface Multimap<K,V>

Parameters:

key - key of entries to remove from the multimap

Returns:

the collection of removed values, or an empty collection if no values were associated with the provided key. The collection may be modifiable, but updating it will have no effect on the multimap.

replaceValues

public Collection<V> replaceValues(K key,
                                   Iterable<? extends V> values)

Description copied from interface: Multimap

Stores a collection of values with the same key, replacing any existing values for that key.

Specified by:

replaceValues in interface Multimap<K,V>

Parameters:

key - key to store in the multimap

values - values to store in the multimap

Returns:

the collection of replaced values, or an empty collection if no values were previously associated with the key. The collection may be modifiable, but updating it will have no effect on the multimap.

size

public int size()

Description copied from interface: Multimap

Returns the number of key-value pairs in the multimap.

Specified by:

size in interface Multimap<K,V>

values

public Collection<V> values()

Description copied from interface: Multimap

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

Specified by:

values in interface Multimap<K,V>

Returns:

collection of values, which may include the same value multiple times if it occurs in multiple mappings

equals

public boolean equals(@Nullable
                      Object object)

Description copied from interface: Multimap

Compares the specified object with this multimap for equality. Two multimaps are equal when their map views, as returned by Multimap.asMap(), are also equal.

In general, two multimaps with identical key-value mappings may or may not be equal, depending on the implementation. For example, two SetMultimap instances with the same key-value mappings are equal, but equality of two ListMultimap instances depends on the ordering of the values for each key.

A non-empty SetMultimap cannot be equal to a non-empty ListMultimap, since their Multimap.asMap() views contain unequal collections as values. However, any two empty multimaps are equal, because they both have empty Multimap.asMap() views.

Specified by:

equals in interface Multimap<K,V>

Overrides:

equals in class Object

hashCode

public int hashCode()

Description copied from interface: Multimap

Returns the hash code for this multimap.

The hash code of a multimap is defined as the hash code of the map view, as returned by Multimap.asMap().

Specified by:

hashCode in interface Multimap<K,V>

Overrides:

hashCode in class Object