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HashMultimap (Guava: Google Core Libraries for Java 11.0.1 API)























  
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com.google.common.collect


Class HashMultimap<K,V>
java.lang.Object
  com.google.common.collect.HashMultimap<K,V>


All Implemented Interfaces: 
Multimap<K,V>, SetMultimap<K,V>, Serializable



@GwtCompatible(serializable=true,
               emulated=true)
public final class HashMultimap<K,V>extends Object




Implementation of Multimap using hash tables.

 
The multimap does not store duplicate key-value pairs. Adding a new
 key-value pair equal to an existing key-value pair has no effect.

 
Keys and values may be null. All optional multimap methods are supported,
 and all returned views are modifiable.

 
This class is not threadsafe when any concurrent operations update the
 multimap. Concurrent read operations will work correctly. To allow concurrent
 update operations, wrap your multimap with a call to Multimaps.synchronizedSetMultimap(com.google.common.collect.SetMultimap).




Since:
  2.0 (imported from Google Collections Library)
Author:
  Jared Levy
See Also:
Serialized Form










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.



static



<K,V> HashMultimap<K,V>



create()



          Creates a new, empty HashMultimap with the default initial
 capacities.



static



<K,V> HashMultimap<K,V>



create(int expectedKeys,
             int expectedValuesPerKey)



          Constructs an empty HashMultimap with enough capacity to hold the
 specified numbers of keys and values without rehashing.



static



<K,V> HashMultimap<K,V>



create(Multimap<? extends K,? extends V> multimap)



          Constructs a HashMultimap with the same mappings as the specified
 multimap.



 Set<Map.Entry<K,V>>
entries()



          Returns a collection of all key-value pairs.



 boolean
equals(Object object)



          Compares the specified object to this multimap for equality.



 Set<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.



 Set<V>
removeAll(Object key)



          Removes all values associated with a given key.



 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.



 int
size()



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



 String
toString()



          Returns a string representation of the multimap, generated by calling
 toString on the map returned by Multimap.asMap().



 Collection<V>
values()



          Returns a collection of all values in the multimap.


 


Methods inherited from class java.lang.Object


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


 


Methods inherited from interface com.google.common.collect.Multimap


clear, containsEntry, containsKey, containsValue, hashCode, isEmpty, keys, keySet, putAll, putAll, remove, size, values


 








Method Detail




create
public static <K,V> HashMultimap<K,V> create()

Creates a new, empty HashMultimap with the default initial
 capacities.








create
public static <K,V> HashMultimap<K,V> create(int expectedKeys,
                                             int expectedValuesPerKey)

Constructs an empty HashMultimap with enough capacity to hold the
 specified numbers of keys and values without rehashing.


Parameters:
expectedKeys - the expected number of distinct keys
expectedValuesPerKey - the expected average number of values per key
Throws:
IllegalArgumentException - if expectedKeys or expectedValuesPerKey is negative





create
public static <K,V> HashMultimap<K,V> create(Multimap<? extends K,? extends V> multimap)

Constructs a HashMultimap with the same mappings as the specified
 multimap. If a key-value mapping appears multiple times in the input
 multimap, it only appears once in the constructed multimap.


Parameters:
multimap - the multimap whose contents are copied to this multimap





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

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.

 
The returned collection is not serializable.

 
Because a SetMultimap has unique values for a given key, this
 method returns a Set, instead of the Collection specified
 in the Multimap interface.


Specified by:
get in interface Multimap<K,V>
Specified by:
get in interface SetMultimap<K,V>


Parameters:
key - key to search for in multimap
Returns:
the collection of values that the key maps to





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

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.

 The iterator generated by the returned collection traverses the values
 for one key, followed by the values of a second key, and so on.

 
Each entry is an immutable snapshot of a key-value mapping in the
 multimap, taken at the time the entry is returned by a method call to the
 collection or its iterator.

 
Because a SetMultimap has unique values for a given key, this
 method returns a Set, instead of the Collection specified
 in the Multimap interface.


Specified by:
entries in interface Multimap<K,V>
Specified by:
entries in interface SetMultimap<K,V>



Returns:
collection of map entries consisting of key-value pairs





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

Removes all values associated with a given key.

 The returned collection is immutable.

 
Because a SetMultimap has unique values for a given key, this
 method returns a Set, instead of the Collection specified
 in the Multimap interface.


Specified by:
removeAll in interface Multimap<K,V>
Specified by:
removeAll in interface SetMultimap<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 Set<V> replaceValues(@Nullable
                            K key,
                            Iterable<? extends V> values)

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

 The returned collection is immutable.

 
Because a SetMultimap has unique values for a given key, this
 method returns a Set, instead of the Collection specified
 in the Multimap interface.

 
Any duplicates in values will be stored in the multimap once.


Specified by:
replaceValues in interface Multimap<K,V>
Specified by:
replaceValues in interface SetMultimap<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.





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

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.

 
Though the method signature doesn't say so explicitly, the returned map
 has Set values.


Specified by:
asMap in interface Multimap<K,V>
Specified by:
asMap in interface SetMultimap<K,V>



Returns:
a map view from a key to its collection of values





put
public boolean put(K key,
                   V value)

Stores a key-value pair in the multimap.


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





equals
public boolean equals(@Nullable
                      Object object)

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.


Specified by:
equals in interface Multimap<K,V>
Specified by:
equals in interface SetMultimap<K,V>








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>








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>








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





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





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





putAll
public boolean putAll(@Nullable
                      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





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>








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





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





values
public Collection<V> values()

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

 The iterator generated by the returned collection traverses the values
 for one key, followed by the values of a second key, and so on.


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





hashCode
public int hashCode()

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


See Also:
Map.hashCode()





toString
public String toString()

Returns a string representation of the multimap, generated by calling
 toString on the map returned by Multimap.asMap().


Overrides:
toString in class Object



Returns:
a string representation of the multimap














  
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Copyright © 2010-2012. All Rights Reserved.

javadoc.com.google.common.collect.HashMultimap.html Maven / Gradle / Ivy

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

create

create

create

get

entries

removeAll

replaceValues

asMap

put

equals

size

isEmpty

containsKey

containsValue

containsEntry

remove

putAll

putAll

clear

keySet

keys

values

hashCode

toString

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