com.google.common.collect

Class HashMultimap<K,V>

java.lang.Object

com.google.common.collect.AbstractMultimap<K,V>

com.google.common.collect.AbstractMapBasedMultimap<K,V>

com.google.common.collect.AbstractSetMultimap<K,V>

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

All Implemented Interfaces:

Multimap<K,V>, SetMultimap<K,V>, java.io.Serializable

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

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<K, V>).

Since:

2.0

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.google.common.collect.AbstractMapBasedMultimap

AbstractMapBasedMultimap.NavigableAsMap, AbstractMapBasedMultimap.NavigableKeySet, AbstractMapBasedMultimap.WrappedNavigableSet

Nested classes/interfaces inherited from class com.google.common.collect.AbstractMultimap

AbstractMultimap.Values

Field Summary

Fields

Modifier and Type	Field and Description
private static int	DEFAULT_VALUES_PER_KEY
(package private) int	expectedValuesPerKey
private static long	serialVersionUID

Constructor Summary

Constructors

Modifier	Constructor and Description
private	HashMultimap()
private	HashMultimap(int expectedKeys, int expectedValuesPerKey)
private	HashMultimap(Multimap<? extends K,? extends V> multimap)

Method Summary

Modifier and Type	Method and Description
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.
(package private) java.util.Set<V>	createCollection() Creates the collection of values for a single key.
private void	readObject(java.io.ObjectInputStream stream)
private void	writeObject(java.io.ObjectOutputStream stream)

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

asMap, createUnmodifiableEmptyCollection, entries, equals, get, put, removeAll, replaceValues

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

backingMap, clear, containsKey, createAsMap, createCollection, createKeySet, entryIterator, setMap, size, unmodifiableCollectionSubclass, valueIterator, values, wrapCollection

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

containsEntry, containsValue, createEntries, createKeys, createValues, hashCode, isEmpty, keys, keySet, putAll, putAll, remove, toString

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

Field Detail

DEFAULT_VALUES_PER_KEY

private static final int DEFAULT_VALUES_PER_KEY

See Also:

Constant Field Values

expectedValuesPerKey

transient int expectedValuesPerKey

serialVersionUID

@GwtIncompatible
private static final long serialVersionUID

See Also:

Constant Field Values

Constructor Detail

HashMultimap

private HashMultimap()

HashMultimap

private HashMultimap(int expectedKeys,
                     int expectedValuesPerKey)

HashMultimap

private HashMultimap(Multimap<? extends K,? extends V> multimap)

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:

java.lang.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

createCollection

java.util.Set<V> createCollection()

Creates the collection of values for a single key.

Collections with weak, soft, or phantom references are not supported. Each call to createCollection should create a new instance.

The returned collection class determines whether duplicate key-value pairs are allowed.

Creates an empty HashSet for a collection of values for one key.

Specified by:

createCollection in class AbstractSetMultimap<K,V>

Returns:

a new HashSet containing a collection of values for one key

writeObject

@GwtIncompatible
private void writeObject(java.io.ObjectOutputStream stream)
                                   throws java.io.IOException

Throws:

java.io.IOException

readObject

@GwtIncompatible
private void readObject(java.io.ObjectInputStream stream)
                                  throws java.io.IOException,
                                         java.lang.ClassNotFoundException

Throws:

java.io.IOException

java.lang.ClassNotFoundException