Package org.apache.commons.collections4.multimap

Class UnmodifiableMultiValuedMap<K,V>

java.lang.Object

org.apache.commons.collections4.multimap.AbstractMultiValuedMapDecorator<K,V>

org.apache.commons.collections4.multimap.UnmodifiableMultiValuedMap<K,V>

Type Parameters:

K - The type of key elements

V - The type of value elements

All Implemented Interfaces:

Serializable, MultiValuedMap<K,V>, Unmodifiable

public final class UnmodifiableMultiValuedMap<K,V>
extends AbstractMultiValuedMapDecorator<K,V>
implements Unmodifiable

Decorates another MultiValuedMap to ensure it can't be altered.

Attempts to modify it will result in an UnsupportedOperationException.

Since:

4.1

See Also:

• Serialized Form

Method Summary

Modifier and Type	Method	Description
Map<K,Collection<V>>	asMap()	Returns a view of this multivalued map as a Map from each distinct key to the non-empty collection of that key's associated values.
void	clear()	Always throws UnsupportedOperationException.
Collection<Map.Entry<K,V>>	entries()	Returns a Collection view of the mappings contained in this multivalued map.
Collection<V>	get(K key)	Gets a view collection of the values associated with the specified key.
MultiSet<K>	keys()	Returns a MultiSet view of the keys contained in this multivalued map.
Set<K>	keySet()	Returns a Set view of the keys contained in this multivalued map.
MapIterator<K,V>	mapIterator()	Obtains a MapIterator over this multivalued map.
boolean	put(K key, V value)	Always throws UnsupportedOperationException.
boolean	putAll(Map<? extends K,? extends V> map)	Always throws UnsupportedOperationException.
boolean	putAll(K key, Iterable<? extends V> values)	Always throws UnsupportedOperationException.
boolean	putAll(MultiValuedMap<? extends K,? extends V> map)	Always throws UnsupportedOperationException.
Collection<V>	remove(Object key)	Always throws UnsupportedOperationException.
boolean	removeMapping(Object key, Object item)	Always throws UnsupportedOperationException.
static <K, V> UnmodifiableMultiValuedMap<K,V>	unmodifiableMultiValuedMap(MultiValuedMap<? extends K,? extends V> map)	Factory method to create an unmodifiable MultiValuedMap.
Collection<V>	values()	Gets a Collection view of all values contained in this multivalued map.

Methods inherited from class org.apache.commons.collections4.multimap.AbstractMultiValuedMapDecorator

containsKey, containsMapping, containsValue, decorated, equals, hashCode, isEmpty, size, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.collections4.MultiValuedMap

inverted

Method Details

unmodifiableMultiValuedMap

public static <K,
V>
UnmodifiableMultiValuedMap<K,V> unmodifiableMultiValuedMap(MultiValuedMap<? extends K,? extends V> map)

Factory method to create an unmodifiable MultiValuedMap.

If the map passed in is already unmodifiable, it is returned.

Type Parameters:

K - The type of key elements

V - The type of value elements

Parameters:

map - The map to decorate, may not be null

Returns:

An unmodifiable MultiValuedMap

Throws:

NullPointerException - if map is null

asMap

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

Description copied from interface: MultiValuedMap

Returns a view of this multivalued map as a Map from each distinct key to the non-empty collection of that key's associated values.

Note that this.asMap().get(k) is equivalent to this.get(k) only when k is a key contained in the multivalued map; otherwise it returns null as opposed to an empty collection.

Changes to the returned map or the collections that serve as its values will update the underlying multivalued map, and vice versa. The map does not support put or putAll, nor do its entries support setValue.

Specified by:

asMap in interface MultiValuedMap<K,V>

Overrides:

asMap in class AbstractMultiValuedMapDecorator<K,V>

Returns:

A map view of the mappings in this multivalued map.

clear

public void clear()

Always throws UnsupportedOperationException.

Specified by:

clear in interface MultiValuedMap<K,V>

Overrides:

clear in class AbstractMultiValuedMapDecorator<K,V>

Throws:

UnsupportedOperationException - Always thrown.

entries

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

Description copied from interface: MultiValuedMap

Returns a Collection view of the mappings contained in this multivalued map.

The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa.

Specified by:

entries in interface MultiValuedMap<K,V>

Overrides:

entries in class AbstractMultiValuedMapDecorator<K,V>

Returns:

A set view of the mappings contained in this map.

get

public Collection<V> get(K key)

Description copied from interface: MultiValuedMap

Gets a view collection of the values associated with the specified key.

This method will return an empty collection if MultiValuedMap.containsKey(Object) returns false. Changes to the returned collection will update the underlying MultiValuedMap and vice-versa.

Specified by:

get in interface MultiValuedMap<K,V>

Overrides:

get in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - The key to retrieve.

Returns:

The Collection of values, implementations should return an empty collection for no mapping.

keys

public MultiSet<K> keys()

Description copied from interface: MultiValuedMap

Returns a MultiSet view of the keys contained in this multivalued map.

The MultiSet.getCount(Object) method of the returned multiset will give the same result a calling get(Object).size() for the same key.

This multiset is backed by the map, so any changes in the map are reflected in the multiset.

Specified by:

keys in interface MultiValuedMap<K,V>

Overrides:

keys in class AbstractMultiValuedMapDecorator<K,V>

Returns:

A multiset view of the keys contained in this map.

keySet

public Set<K> keySet()

Description copied from interface: MultiValuedMap

Returns a Set view of the keys contained in this multivalued map.

The set is backed by the map, so changes to the map are reflected in the set, and vice-versa.

If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation), the result of the iteration is undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Specified by:

keySet in interface MultiValuedMap<K,V>

Overrides:

keySet in class AbstractMultiValuedMapDecorator<K,V>

Returns:

A set view of the keys contained in this map.

mapIterator

public MapIterator<K,V> mapIterator()

Obtains a MapIterator over this multivalued map.

A map iterator is an efficient way of iterating over maps. There is no need to access the entries collection or use Map.Entry objects.

The returned map iterator's MapIterator.setValue(Object) method is not supported and will throw an UnsupportedOperationException.

Specified by:

mapIterator in interface MultiValuedMap<K,V>

Overrides:

mapIterator in class AbstractMultiValuedMapDecorator<K,V>

Returns:

A map iterator.

put

public boolean put(K key,
 V value)

Always throws UnsupportedOperationException.

Specified by:

put in interface MultiValuedMap<K,V>

Overrides:

put in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - Ignored.

value - The value to add to the collection at the key.

Returns:

true if the map changed as a result of this put operation, or false if the map already contained the key-value mapping and the collection type does not allow duplicate values, for example when using a Set.

Throws:

UnsupportedOperationException - Always thrown.

putAll

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

Always throws UnsupportedOperationException.

Specified by:

putAll in interface MultiValuedMap<K,V>

Overrides:

putAll in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - Ignored.

values - Ignored.

Returns:

true if the map changed as a result of this operation.

Throws:

UnsupportedOperationException - Always thrown.

putAll

public boolean putAll(Map<? extends K,? extends V> map)

Always throws UnsupportedOperationException.

Specified by:

putAll in interface MultiValuedMap<K,V>

Overrides:

putAll in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

map - Ignored.

Returns:

true if the map changed as a result of this operation.

Throws:

UnsupportedOperationException - Always thrown.

putAll

public boolean putAll(MultiValuedMap<? extends K,? extends V> map)

Always throws UnsupportedOperationException.

Specified by:

putAll in interface MultiValuedMap<K,V>

Overrides:

putAll in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

map - Ignored.

Returns:

true if the map changed as a result of this operation.

Throws:

UnsupportedOperationException - Always thrown.

remove

public Collection<V> remove(Object key)

Always throws UnsupportedOperationException.

Specified by:

remove in interface MultiValuedMap<K,V>

Overrides:

remove in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - Ignored.

Returns:

The values that were removed.

Throws:

UnsupportedOperationException - Always thrown.

removeMapping

public boolean removeMapping(Object key,
 Object item)

Always throws UnsupportedOperationException.

Specified by:

removeMapping in interface MultiValuedMap<K,V>

Overrides:

removeMapping in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - Ignored.

item - Ignored.

Returns:

true if the mapping was removed, false otherwise.

Throws:

UnsupportedOperationException - Always thrown.

values

public Collection<V> values()

Description copied from interface: MultiValuedMap

Gets a Collection view of all values contained in this multivalued map.

Implementations typically return a collection containing the combination of values from all keys.

Specified by:

values in interface MultiValuedMap<K,V>

Overrides:

values in class AbstractMultiValuedMapDecorator<K,V>

Returns:

A collection view of the values contained in this multivalued map.