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:

java.io.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
java.util.Map<K,java.util.Collection<V>>	asMap()	Returns a view of this multi-valued map as a Map from each distinct key to the non-empty collection of that key's associated values.
void	clear()	Removes all of the mappings from this map (optional operation).
java.util.Collection<java.util.Map.Entry<K,V>>	entries()	Returns a Collection view of the mappings contained in this multi-valued map.
java.util.Collection<V>	get(K key)	Returns a view collection of the values associated with the specified key.
MultiSet<K>	keys()	Returns a MultiSet view of the keys contained in this multi-valued map.
java.util.Set<K>	keySet()	Returns a Set view of the keys contained in this multi-valued map.
MapIterator<K,V>	mapIterator()	Obtains a MapIterator over this multi-valued map.
boolean	put(K key, V value)	Adds a key-value mapping to this multi-valued map.
boolean	putAll(java.util.Map<? extends K,? extends V> map)	Copies all mappings from the specified map to this multi-valued map (optional operation).
boolean	putAll(K key, java.lang.Iterable<? extends V> values)	Adds a mapping to the specified key for all values contained in the given Iterable.
boolean	putAll(MultiValuedMap<? extends K,? extends V> map)	Copies all mappings from the specified map to this multi-valued map (optional operation).
java.util.Collection<V>	remove(java.lang.Object key)	Removes all values associated with the specified key.
boolean	removeMapping(java.lang.Object key, java.lang.Object item)	Removes a key-value mapping from the map.
static <K,V> UnmodifiableMultiValuedMap<K,V>	unmodifiableMultiValuedMap(MultiValuedMap<? extends K,? extends V> map)	Factory method to create an unmodifiable MultiValuedMap.
java.util.Collection<V>	values()	Gets a Collection view of all values contained in this multi-valued map.

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

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

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

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:

java.lang.NullPointerException - if map is null

remove

public java.util.Collection<V> remove(java.lang.Object key)

Description copied from interface: MultiValuedMap

Removes all values associated with the specified key.

The returned collection may be modifiable, but updates will not be propagated to this multi-valued map. In case no mapping was stored for the specified key, an empty, unmodifiable collection will be returned.

Specified by:

remove in interface MultiValuedMap<K,V>

Overrides:

remove in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - the key to remove values from

Returns:

the values that were removed

removeMapping

public boolean removeMapping(java.lang.Object key,
                             java.lang.Object item)

Description copied from interface: MultiValuedMap

Removes a key-value mapping from the map.

The item is removed from the collection mapped to the specified key. Other values attached to that key are unaffected.

If the last value for a key is removed, implementations typically return an empty collection from a subsequent get(Object).

Specified by:

removeMapping in interface MultiValuedMap<K,V>

Overrides:

removeMapping in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - the key to remove from

item - the item to remove

Returns:

true if the mapping was removed, false otherwise

clear

public void clear()

Description copied from interface: MultiValuedMap

Removes all of the mappings from this map (optional operation).

The map will be empty after this call returns.

Specified by:

clear in interface MultiValuedMap<K,V>

Overrides:

clear in class AbstractMultiValuedMapDecorator<K,V>

get

public java.util.Collection<V> get(K key)

Description copied from interface: MultiValuedMap

Returns 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

put

public boolean put(K key,
                   V value)

Description copied from interface: MultiValuedMap

Adds a key-value mapping to this multi-valued map.

Unlike a normal Map the previous value is not replaced. Instead the new value is added to the collection stored against the key. Depending on the collection type used, duplicate key-value mappings may be allowed.

The method will return true if the size of the multi-valued map has been increased because of this operation.

Specified by:

put in interface MultiValuedMap<K,V>

Overrides:

put in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - the key to store against

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, e.g. when using a Set

keySet

public java.util.Set<K> keySet()

Description copied from interface: MultiValuedMap

Returns a Set view of the keys contained in this multi-valued 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

entries

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

Description copied from interface: MultiValuedMap

Returns a Collection view of the mappings contained in this multi-valued 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

keys

public MultiSet<K> keys()

Description copied from interface: MultiValuedMap

Returns a MultiSet view of the keys contained in this multi-valued 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

values

public java.util.Collection<V> values()

Description copied from interface: MultiValuedMap

Gets a Collection view of all values contained in this multi-valued 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 multi-valued map

asMap

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

Description copied from interface: MultiValuedMap

Returns a view of this multi-valued 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 multi-valued 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 multi-valued 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 multi-valued map

mapIterator

public MapIterator<K,V> mapIterator()

Description copied from interface: MultiValuedMap

Obtains a MapIterator over this multi-valued 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.

Specified by:

mapIterator in interface MultiValuedMap<K,V>

Overrides:

mapIterator in class AbstractMultiValuedMapDecorator<K,V>

Returns:

a map iterator

putAll

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

Description copied from interface: MultiValuedMap

Adds a mapping to the specified key for all values contained in the given Iterable.

Specified by:

putAll in interface MultiValuedMap<K,V>

Overrides:

putAll in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

key - the key to store against

values - the values to add to the collection at the key, may not be null

Returns:

true if the map changed as a result of this operation

putAll

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

Description copied from interface: MultiValuedMap

Copies all mappings from the specified map to this multi-valued map (optional operation).

The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map.

The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Specified by:

putAll in interface MultiValuedMap<K,V>

Overrides:

putAll in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

map - mappings to be stored in this map, may not be null

Returns:

true if the map changed as a result of this operation

putAll

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

Description copied from interface: MultiValuedMap

Copies all mappings from the specified map to this multi-valued map (optional operation).

The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map.

The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Specified by:

putAll in interface MultiValuedMap<K,V>

Overrides:

putAll in class AbstractMultiValuedMapDecorator<K,V>

Parameters:

map - mappings to be stored in this map, may not be null

Returns:

true if the map changed as a result of this operation