edu.ucla.sspace.util

Class HashMultiMap<K,V>

java.lang.Object

edu.ucla.sspace.util.HashMultiMap<K,V>

All Implemented Interfaces:

MultiMap<K,V>, Serializable

public class HashMultiMap<K,V>
extends Object
implements MultiMap<K,V>, Serializable

A hash table based implementation of the MultiMap interface. This implementation permits both null keys and values.

This implementation provides constant time operations for the basic operations put and get, assuming a uniform distribution of hash keys.

See Also:

HashMap, Serialized Form

Constructor Summary

Constructors

Constructor and Description
HashMultiMap()
HashMultiMap(Map<? extends K,? extends V> m) Constructs this map and adds in all the mapping from the provided Map

Method Summary

Methods

Modifier and Type	Method and Description
Map<K,Set<V>>	asMap() Returns a Map-based view of this MultiMap
void	clear() Removes all of the mappings from this multi-map.
boolean	containsKey(Object key) Returns true if this multi-map contains a mapping for the specified key.
boolean	containsMapping(Object key, Object value) Returns true if this multi-map contains a mapping from specified key to the specified value.
boolean	containsValue(Object value) Returns true if this multi-map contains from any key to the specified value.
Set<Map.Entry<K,V>>	entrySet() Returns a Set view of all the key-value mappings contained in this multi-map.
Set<V>	get(Object key) Returns the set of values mapped to this key or null of the key is not mapped to any values
boolean	isEmpty() Returns true if this multi-map contains no mappings.
Set<K>	keySet() Returns a Set view of the mappings contained in this multi-map.
boolean	put(K key, V value) Adds the specified value to the set of values associated with the specified key in this map.
void	putAll(Map<? extends K,? extends V> m) Copies all of the mappings from the specified map to this mutli-map
void	putAll(MultiMap<? extends K,? extends V> m) Copies all of the mappings from the specified mulit-map to this mutli-map
boolean	putMany(K key, Collection<V> values) Adds all of the specified values to the set of values associated with the specified key in this map.
int	range() Returns the number of values maped to keys.
Set<V>	remove(Object key) Removes the mapping for a key from this multi-map if it is present, returning any mapped values to that key
boolean	remove(Object key, Object value) Removes the specified mapping for a key if it is present.
int	size() Returns the number of keys that are mapped to one or more values in this multi-map.
String	toString() Returns the string form of this multi-map
Collection<V>	values() Returns a Collection view of the values contained in this map.
Collection<Set<V>>	valueSets() Returns a Collection view of the sets of values mapped to each key in this map.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

HashMultiMap

public HashMultiMap()

HashMultiMap

public HashMultiMap(Map<? extends K,? extends V> m)

Constructs this map and adds in all the mapping from the provided Map

Method Detail

asMap

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

Returns a Map-based view of this MultiMap

Specified by:

asMap in interface MultiMap<K,V>

clear

public void clear()

Removes all of the mappings from this multi-map.

Specified by:

clear in interface MultiMap<K,V>

containsKey

public boolean containsKey(Object key)

Returns true if this multi-map contains a mapping for the specified key.

Specified by:

containsKey in interface MultiMap<K,V>

containsMapping

public boolean containsMapping(Object key,
                      Object value)

Returns true if this multi-map contains a mapping from specified key to the specified value.

Specified by:

containsMapping in interface MultiMap<K,V>

containsValue

public boolean containsValue(Object value)

Returns true if this multi-map contains from any key to the specified value.

Specified by:

containsValue in interface MultiMap<K,V>

entrySet

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

Returns a Set view of all the key-value mappings contained in this multi-map.

Specified by:

entrySet in interface MultiMap<K,V>

get

public Set<V> get(Object key)

Returns the set of values mapped to this key or null of the key is not mapped to any values

Specified by:

get in interface MultiMap<K,V>

isEmpty

public boolean isEmpty()

Returns true if this multi-map contains no mappings.

Specified by:

isEmpty in interface MultiMap<K,V>

keySet

public Set<K> keySet()

Returns a Set view of the mappings contained in this multi-map.

Specified by:

keySet in interface MultiMap<K,V>

put

public boolean put(K key,
          V value)

Adds the specified value to the set of values associated with the specified key in this map.

Specified by:

put in interface MultiMap<K,V>

Parameters:

key - key with which the specified value is to be associated

value - a value to be associated with the specified key

Returns:

true if the provided value was not already in the set of value mapped to the specified key

putAll

public void putAll(Map<? extends K,? extends V> m)

Copies all of the mappings from the specified map to this mutli-map

Specified by:

putAll in interface MultiMap<K,V>

putAll

public void putAll(MultiMap<? extends K,? extends V> m)

Copies all of the mappings from the specified mulit-map to this mutli-map

Specified by:

putAll in interface MultiMap<K,V>

putMany

public boolean putMany(K key,
              Collection<V> values)

Adds all of the specified values to the set of values associated with the specified key in this map.

Specified by:

putMany in interface MultiMap<K,V>

Parameters:

key - key with which the specified value is to be associated

values - a collection of values to be associated with the specified key

Returns:

true if at least one of the provided value was not already in the set of value mapped to the specified key

range

public int range()

Returns the number of values maped to keys. Note that in the bijective case, this will equal the value returned by MultiMap.size(). However, in the case where a key is mapped to more than one value, this method will always return a value strictly larger than size().

Specified by:

range in interface MultiMap<K,V>

Returns:

the number of values maped to keys

remove

public Set<V> remove(Object key)

Removes the mapping for a key from this multi-map if it is present, returning any mapped values to that key

Specified by:

remove in interface MultiMap<K,V>

Returns:

the set of values mapped to the key or the empty set if the key was not present

remove

public boolean remove(Object key,
             Object value)

Removes the specified mapping for a key if it is present. If the key is mapped to other values, it is retained, otherwise the key is removed from the map. This method provides a way to remove a specific mapping for a key without removing all other existing mappings.

Specified by:

remove in interface MultiMap<K,V>

Returns:

true if the specified mapping was removed

size

public int size()

Returns the number of keys that are mapped to one or more values in this multi-map.

Specified by:

size in interface MultiMap<K,V>

See Also:

MultiMap.range()

toString

public String toString()

Returns the string form of this multi-map

Overrides:

toString in class Object

values

public Collection<V> values()

Returns a Collection view of the values contained in this map. The collection and its Iterator are backed by the map, so changes to the map are reflected in the collection, and vice-versa.

Specified by:

values in interface MultiMap<K,V>

valueSets

public Collection<Set<V>> valueSets()

Returns a Collection view of the sets of values mapped to each key in this map.

Specified by:

valueSets in interface MultiMap<K,V>