Interface SetMultimap<K extends @Nullable Object,V extends @Nullable Object>
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- All Superinterfaces:
Multimap<K,V>
- All Known Subinterfaces:
SortedSetMultimap<K,V>
- All Known Implementing Classes:
ForwardingSetMultimap
,ForwardingSortedSetMultimap
,HashMultimap
,ImmutableSetMultimap
,LinkedHashMultimap
,TreeMultimap
@GwtCompatible public interface SetMultimap<K extends @Nullable Object,V extends @Nullable Object> extends Multimap<K,V>
AMultimap
that cannot hold duplicate key-value pairs. Adding a key-value pair that's already in the multimap has no effect. See theMultimap
documentation for information common to all multimaps.The
get(K)
,removeAll(java.lang.Object)
, andreplaceValues(K, java.lang.Iterable<? extends V>)
methods each return aSet
of values, whileentries()
returns aSet
of map entries. Though the method signature doesn't say so explicitly, the map returned byasMap()
hasSet
values.If the values corresponding to a single key should be ordered according to a
Comparator
(or the natural order), see theSortedSetMultimap
subinterface.Since the value collections are sets, the behavior of a
SetMultimap
is not specified if key or value objects already present in the multimap change in a manner that affectsequals
comparisons. Use caution if mutable objects are used as keys or values in aSetMultimap
.Warning: Do not modify either a key or a value of a
SetMultimap
in a way that affects itsObject.equals(java.lang.Object)
behavior. Undefined behavior and bugs will result.See the Guava User Guide article on
Multimap
.- Since:
- 2.0
- Author:
- Jared Levy
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description Map<K,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.Set<Map.Entry<K,V>>
entries()
Returns a view collection of all key-value pairs contained in this multimap, asMap.Entry
instances.boolean
equals(Object obj)
Compares the specified object to this multimap for equality.Set<V>
get(K key)
Returns a view collection of the values associated withkey
in this multimap, if any.Set<V>
removeAll(Object key)
Removes all values associated with the keykey
.Set<V>
replaceValues(K key, Iterable<? extends V> values)
Stores a collection of values with the same key, replacing any existing values for that key.
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Method Detail
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get
Set<V> get(K key)
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.
Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.
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removeAll
@CanIgnoreReturnValue Set<V> removeAll(@CheckForNull Object key)
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.Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.
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replaceValues
@CanIgnoreReturnValue Set<V> replaceValues(K key, Iterable<? extends V> values)
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)
.Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.Any duplicates in
values
will be stored in the multimap once.- Specified by:
replaceValues
in interfaceMultimap<K extends @Nullable Object,V extends @Nullable 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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entries
Set<Map.Entry<K,V>> entries()
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.
Because a
SetMultimap
has unique values for a given key, this method returns aSet
, instead of theCollection
specified in theMultimap
interface.
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asMap
Map<K,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. 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
.Note: The returned map's values are guaranteed to be of type
Set
. To obtain this map with the more specific generic typeMap<K, Set<V>>
, callMultimaps.asMap(SetMultimap)
instead.
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equals
boolean equals(@CheckForNull Object obj)
Compares the specified object to this multimap for equality.Two
SetMultimap
instances are equal if, for each key, they contain the same values. Equality does not depend on the ordering of keys or values.An empty
SetMultimap
is equal to any other emptyMultimap
, including an emptyListMultimap
.
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