Class ForwardingMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- java.lang.Object
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- com.google.common.collect.ForwardingObject
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- com.google.common.collect.ForwardingMultimap<K,V>
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- All Implemented Interfaces:
Multimap<K,V>
- Direct Known Subclasses:
ForwardingListMultimap
,ForwardingSetMultimap
@GwtCompatible public abstract class ForwardingMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object> 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.default
method warning: This class does not forward calls todefault
methods. Instead, it inherits their default implementations. When those implementations invoke methods, they invoke methods on theForwardingMultimap
.- Since:
- 2.0
- Author:
- Robert Konigsberg
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Constructor Summary
Constructors Modifier Constructor Description protected
ForwardingMultimap()
Constructor for use by subclasses.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description java.util.Map<K,java.util.Collection<V>>
asMap()
Returns a view of this multimap as aMap
from each distinct key to the nonempty collection of that key's associated values.void
clear()
Removes all key-value pairs from the multimap, leaving it empty.boolean
containsEntry(java.lang.Object key, java.lang.Object value)
Returnstrue
if this multimap contains at least one key-value pair with the keykey
and the valuevalue
.boolean
containsKey(java.lang.Object key)
Returnstrue
if this multimap contains at least one key-value pair with the keykey
.boolean
containsValue(java.lang.Object value)
Returnstrue
if this multimap contains at least one key-value pair with the valuevalue
.protected abstract Multimap<K,V>
delegate()
Returns the backing delegate instance that methods are forwarded to.java.util.Collection<java.util.Map.Entry<K,V>>
entries()
Returns a view collection of all key-value pairs contained in this multimap, asMap.Entry
instances.boolean
equals(java.lang.Object object)
Compares the specified object with this multimap for equality.java.util.Collection<V>
get(K key)
Returns a view collection of the values associated withkey
in this multimap, if any.int
hashCode()
Returns the hash code for this multimap.boolean
isEmpty()
Returnstrue
if this multimap contains no key-value pairs.Multiset<K>
keys()
Returns a view collection containing the key from each key-value pair in this multimap, without collapsing duplicates.java.util.Set<K>
keySet()
Returns a view collection of all distinct keys contained in this multimap.boolean
put(K key, V value)
Stores a key-value pair in this multimap.boolean
putAll(Multimap<? extends K,? extends V> multimap)
Stores all key-value pairs ofmultimap
in this multimap, in the order returned bymultimap.entries()
.boolean
putAll(K key, java.lang.Iterable<? extends V> values)
Stores a key-value pair in this multimap for each ofvalues
, all using the same key,key
.boolean
remove(java.lang.Object key, java.lang.Object value)
Removes a single key-value pair with the keykey
and the valuevalue
from this multimap, if such exists.java.util.Collection<V>
removeAll(java.lang.Object key)
Removes all values associated with the keykey
.java.util.Collection<V>
replaceValues(K key, java.lang.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 this multimap.java.util.Collection<V>
values()
Returns a view collection containing the value from each key-value pair contained in this multimap, without collapsing duplicates (sovalues().size() == size()
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Methods inherited from class com.google.common.collect.ForwardingObject
toString
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Constructor Detail
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ForwardingMultimap
protected ForwardingMultimap()
Constructor for use by subclasses.
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Method Detail
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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 asForwardingSet.delegate()
. Concrete subclasses override this method to supply the instance being decorated.- Specified by:
delegate
in classForwardingObject
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asMap
public java.util.Map<K,java.util.Collection<V>> asMap()
Description copied from interface:Multimap
Returns a view of this multimap as aMap
from each distinct key to the nonempty collection of that key's associated values. Note thatthis.asMap().get(k)
is equivalent tothis.get(k)
only whenk
is a key contained in the multimap; otherwise it returnsnull
as opposed to an empty collection.Changes to the returned map or the collections that serve as its values will update the underlying multimap, and vice versa. The map does not support
put
orputAll
, nor do its entries supportsetValue
.
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clear
public void clear()
Description copied from interface:Multimap
Removes all key-value pairs from the multimap, leaving it empty.
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containsEntry
public boolean containsEntry(@CheckForNull java.lang.Object key, @CheckForNull java.lang.Object value)
Description copied from interface:Multimap
Returnstrue
if this multimap contains at least one key-value pair with the keykey
and the valuevalue
.
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containsKey
public boolean containsKey(@CheckForNull java.lang.Object key)
Description copied from interface:Multimap
Returnstrue
if this multimap contains at least one key-value pair with the keykey
.
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containsValue
public boolean containsValue(@CheckForNull java.lang.Object value)
Description copied from interface:Multimap
Returnstrue
if this multimap contains at least one key-value pair with the valuevalue
.
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entries
public java.util.Collection<java.util.Map.Entry<K,V>> entries()
Description copied from interface:Multimap
Returns a view collection of all key-value pairs contained in this multimap, asMap.Entry
instances.Changes to the returned collection or the entries it contains will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
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get
public java.util.Collection<V> get(K key)
Description copied from interface:Multimap
Returns a view collection of the values associated withkey
in this multimap, if any. Note that whencontainsKey(key)
is false, this returns an empty collection, notnull
.Changes to the returned collection will update the underlying multimap, and vice versa.
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isEmpty
public boolean isEmpty()
Description copied from interface:Multimap
Returnstrue
if this multimap contains no key-value pairs. Equivalent tosize() == 0
, but can in some cases be more efficient.
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keys
public Multiset<K> keys()
Description copied from interface:Multimap
Returns a view collection containing the key from each key-value pair in this multimap, without collapsing duplicates. This collection has the same size as this multimap, andkeys().count(k) == get(k).size()
for allk
.Changes to the returned multiset will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
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keySet
public java.util.Set<K> keySet()
Description copied from interface:Multimap
Returns a view collection of all distinct keys contained in this multimap. Note that the key set contains a key if and only if this multimap maps that key to at least one value.Changes to the returned set will update the underlying multimap, and vice versa. However, adding to the returned set is not possible.
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put
@CanIgnoreReturnValue public boolean put(K key, V value)
Description copied from interface:Multimap
Stores a key-value pair in this 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.
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putAll
@CanIgnoreReturnValue public boolean putAll(K key, java.lang.Iterable<? extends V> values)
Description copied from interface:Multimap
Stores a key-value pair in this multimap for each ofvalues
, all using the same key,key
. Equivalent to (but expected to be more efficient than):for (V value : values) { put(key, value); }
In particular, this is a no-op if
values
is empty.
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putAll
@CanIgnoreReturnValue public boolean putAll(Multimap<? extends K,? extends V> multimap)
Description copied from interface:Multimap
Stores all key-value pairs ofmultimap
in this multimap, in the order returned bymultimap.entries()
.
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remove
@CanIgnoreReturnValue public boolean remove(@CheckForNull java.lang.Object key, @CheckForNull java.lang.Object value)
Description copied from interface:Multimap
Removes a single key-value pair with the keykey
and the valuevalue
from this multimap, if such exists. If multiple key-value pairs in the multimap fit this description, which one is removed is unspecified.
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removeAll
@CanIgnoreReturnValue public java.util.Collection<V> removeAll(@CheckForNull java.lang.Object key)
Description copied from interface:Multimap
Removes all values associated with the keykey
.Once this method returns,
key
will not be mapped to any values, so it will not appear inMultimap.keySet()
,Multimap.asMap()
, or any other views.
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replaceValues
@CanIgnoreReturnValue public java.util.Collection<V> replaceValues(K key, java.lang.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.If
values
is empty, this is equivalent toremoveAll(key)
.- Specified by:
replaceValues
in interfaceMultimap<K extends @Nullable java.lang.Object,V extends @Nullable java.lang.Object>
- 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.
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size
public int size()
Description copied from interface:Multimap
Returns the number of key-value pairs in this multimap.Note: this method does not return the number of distinct keys in the multimap, which is given by
keySet().size()
orasMap().size()
. See the opening section of theMultimap
class documentation for clarification.
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values
public java.util.Collection<V> values()
Description copied from interface:Multimap
Returns a view collection containing the value from each key-value pair contained in this multimap, without collapsing duplicates (sovalues().size() == size()
).Changes to the returned collection will update the underlying multimap, and vice versa. However, adding to the returned collection is not possible.
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equals
public boolean equals(@CheckForNull java.lang.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 byMultimap.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 twoListMultimap
instances depends on the ordering of the values for each key.A non-empty
SetMultimap
cannot be equal to a non-emptyListMultimap
, since theirMultimap.asMap()
views contain unequal collections as values. However, any two empty multimaps are equal, because they both have emptyMultimap.asMap()
views.
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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()
.In general, two multimaps with identical key-value mappings may or may not have the same hash codes, depending on the implementation. For example, two
SetMultimap
instances with the same key-value mappings will have the samehashCode
, but thehashCode
ofListMultimap
instances depends on the ordering of the values for each key.
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