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

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

All Implemented Interfaces:

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

public class ImmutableMultimap<K,V>
extends java.lang.Object
implements ListMultimap<K,V>, java.io.Serializable

An immutable ListMultimap with reliable user-specified key and value iteration order. Does not permit null keys or values.

Unlike Multimaps.unmodifiableListMultimap(ListMultimap), which is a view of a separate map which can still change, an instance of ImmutableMultimap contains its own data and will never change. ImmutableMultimap is convenient for public static final multimaps ("constant multimaps") and also lets you easily make a "defensive copy" of a multimap provided to your class by a caller.

Note: Although this class is not final, it cannot be subclassed as it has no public or protected constructors. Thus, instances of this class are guaranteed to be immutable.

Author:

Jared Levy

See Also:

Serialized Form

Nested Class Summary

static class

ImmutableMultimap.Builder<K,V> A builder for creating immutable multimap instances, especially public static final multimaps ("constant multimaps").

Method Summary

ImmutableMap<K,java.util.Collection<V>>	asMap() Returns an immutable map that associates each key with its corresponding values in the multimap.
static <K,V> ImmutableMultimap.Builder<K,V>	builder() Returns a new builder.
void	clear() Guaranteed to throw an exception and leave the multimap unmodified.
boolean	containsEntry(java.lang.Object key, java.lang.Object value) Returns true if the multimap contains the specified key-value pair.
boolean	containsKey(java.lang.Object key) Returns true if the multimap contains any values for the specified key.
boolean	containsValue(java.lang.Object value) Returns true if the multimap contains the specified value for any key.
static <K,V> ImmutableMultimap<K,V>	copyOf(Multimap<? extends K,? extends V> multimap) Returns an immutable multimap containing the same mappings as multimap.
static <K,V> ImmutableMultimap<K,V>	empty() Returns the empty multimap.
ImmutableCollection<java.util.Map.Entry<K,V>>	entries() Returns an immutable collection of all key-value pairs in the multimap.
boolean	equals(java.lang.Object obj) Compares the specified object to this multimap for equality.
ImmutableList<V>	get(K key) Returns an immutable list of the values for the given key.
int	hashCode() Returns the hash code for this multimap.
boolean	isEmpty() Returns true if the multimap contains no key-value pairs.
ImmutableMultiset<K>	keys() Returns a collection, which may contain duplicates, of all keys.
ImmutableSet<K>	keySet() Returns an immutable set of the distinct keys in this multimap.
boolean	put(K key, V value) Guaranteed to throw an exception and leave the multimap unmodified.
boolean	putAll(K key, java.lang.Iterable<? extends V> values) Guaranteed to throw an exception and leave the multimap unmodified.
boolean	putAll(Multimap<? extends K,? extends V> multimap) Guaranteed to throw an exception and leave the multimap unmodified.
boolean	remove(java.lang.Object key, java.lang.Object value) Guaranteed to throw an exception and leave the multimap unmodified.
java.util.List<V>	removeAll(java.lang.Object key) Guaranteed to throw an exception and leave the multimap unmodified.
java.util.List<V>	replaceValues(K key, java.lang.Iterable<? extends V> values) Guaranteed to throw an exception and leave the multimap unmodified.
int	size() Returns the number of key-value pairs in the multimap.
java.lang.String	toString()
ImmutableCollection<V>	values() Returns an immutable collection of the values in this multimap.

Methods inherited from class java.lang.Object

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

Method Detail

empty

public static <K,V> ImmutableMultimap<K,V> empty()

Returns the empty multimap.

builder

public static <K,V> ImmutableMultimap.Builder<K,V> builder()

Returns a new builder. The generated builder is equivalent to the builder created by the ImmutableMultimap.Builder constructor.

copyOf

public static <K,V> ImmutableMultimap<K,V> copyOf(Multimap<? extends K,? extends V> multimap)

Returns an immutable multimap containing the same mappings as multimap. The generated multimap's key and value orderings correspond to the iteration ordering of the multimap.asMap() view.

Note: Despite what the method name suggests, if multimap is an ImmutableMultimap, no copy will actually be performed, and the given map itself will be returned.

Throws:

java.lang.NullPointerException - if any key or value in multimap is null

removeAll

public java.util.List<V> removeAll(java.lang.Object key)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

removeAll in interface ListMultimap<K,V>

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.

Throws:

java.lang.UnsupportedOperationException - always

replaceValues

public java.util.List<V> replaceValues(K key,
                                       java.lang.Iterable<? extends V> values)

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

replaceValues in interface ListMultimap<K,V>

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.

Throws:

java.lang.UnsupportedOperationException - always

clear

public void clear()

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

clear in interface Multimap<K,V>

Throws:

java.lang.UnsupportedOperationException - always

put

public boolean put(K key,
                   V value)

Guaranteed to throw an exception and leave the multimap unmodified.

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

Throws:

java.lang.UnsupportedOperationException - always

putAll

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

Guaranteed to throw an exception and leave the multimap unmodified.

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

Throws:

java.lang.UnsupportedOperationException - always

putAll

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

Guaranteed to throw an exception and leave the multimap unmodified.

Specified by:

putAll in interface Multimap<K,V>

Parameters:

multimap - mappings to store in this multimap

Returns:

true if the multimap changed

Throws:

java.lang.UnsupportedOperationException - always

remove

public boolean remove(java.lang.Object key,
                      java.lang.Object value)

Guaranteed to throw an exception and leave the multimap unmodified.

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

Throws:

java.lang.UnsupportedOperationException - always

containsEntry

public boolean containsEntry(@Nullable
                             java.lang.Object key,
                             @Nullable
                             java.lang.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
                           java.lang.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
                             java.lang.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

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>

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>

equals

public boolean equals(@Nullable
                      java.lang.Object obj)

Description copied from interface: ListMultimap

Compares the specified object to this multimap for equality.

Two ListMultimap instances are equal if, for each key, they contain the same values in the same order. If the value orderings disagree, the multimaps will not be considered equal.

Specified by:

equals in interface ListMultimap<K,V>

Specified by:

equals in interface Multimap<K,V>

Overrides:

equals in class java.lang.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 java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

get

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

Returns an immutable list of the values for the given key. If no mappings in the multimap have the provided key, an empty immutable list is returned. The values are in the same order as the parameters used to build this multimap.

Specified by:

get in interface ListMultimap<K,V>

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

keySet

public ImmutableSet<K> keySet()

Returns an immutable set of the distinct keys in this multimap. These keys are ordered according to when they first appeared during the construction of this multimap.

Specified by:

keySet in interface Multimap<K,V>

Returns:

the collection of distinct keys

asMap

public ImmutableMap<K,java.util.Collection<V>> asMap()

Returns an immutable map that associates each key with its corresponding values in the multimap. Though the method signature doesn't say so explicitly, the returned map has ImmutableList values.

Specified by:

asMap in interface ListMultimap<K,V>

Specified by:

asMap in interface Multimap<K,V>

Returns:

a map view from a key to its collection of values

entries

public ImmutableCollection<java.util.Map.Entry<K,V>> entries()

Returns an immutable collection of all key-value pairs in the multimap. Its iterator traverses the values for the first key, the values for the second key, and so on.

Specified by:

entries in interface Multimap<K,V>

Returns:

collection of map entries consisting of key-value pairs

keys

public ImmutableMultiset<K> keys()

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. Duplicate keys appear consecutively in the multiset's iteration order.

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 ImmutableCollection<V> values()

Returns an immutable collection of the values in this multimap. Its iterator traverses the values for the first key, the values for the 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