public class MultiValueMap<K,V> extends AbstractMapDecorator<K,Object> implements MultiMap<K,V>, Serializable
A MultiMap is a Map with slightly different semantics.
Putting a value into the map will add the value to a Collection at that key.
Getting a value will return a Collection, holding all the values put to that key.
This implementation is a decorator, allowing any Map implementation to be used as the base.
In addition, this implementation allows the type of collection used
for the values to be controlled. By default, an ArrayList
is used, however a Class to instantiate may be specified,
or a factory that returns a Collection instance.
Note that MultiValueMap is not synchronized and is not thread-safe. If you wish to use this map from multiple threads concurrently, you must use appropriate synchronization. This class may throw exceptions when accessed by concurrent threads without synchronization.
| Modifier | Constructor and Description |
|---|---|
|
MultiValueMap()
Creates a MultiValueMap based on a
HashMap and
storing the multiple values in an ArrayList. |
protected |
MultiValueMap(Map<K,? super C> map,
Factory<C> collectionFactory)
Creates a MultiValueMap which decorates the given
map and
creates the value collections using the supplied collectionFactory. |
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Clear the map.
|
boolean |
containsValue(Object value)
Checks whether the map contains the value specified.
|
boolean |
containsValue(Object key,
Object value)
Checks whether the collection at the specified key contains the value.
|
protected Collection<V> |
createCollection(int size)
Creates a new instance of the map value Collection container
using the factory.
|
Set<Map.Entry<K,Object>> |
entrySet() |
Collection<V> |
getCollection(Object key)
Gets the collection mapped to the specified key.
|
Iterator<Map.Entry<K,V>> |
iterator()
Gets an iterator for all mappings stored in this
MultiValueMap. |
Iterator<V> |
iterator(Object key)
Gets an iterator for the collection mapped to the specified key.
|
static <K,V,C extends Collection<V>> |
multiValueMap(Map<K,? super C> map,
Class<C> collectionClass)
Creates a map which decorates the given
map and
maps keys to collections of type collectionClass. |
static <K,V,C extends Collection<V>> |
multiValueMap(Map<K,? super C> map,
Factory<C> collectionFactory)
Creates a map which decorates the given
map and
creates the value collections using the supplied collectionFactory. |
static <K,V> MultiValueMap<K,V> |
multiValueMap(Map<K,? super Collection<V>> map)
Creates a map which wraps the given map and
maps keys to ArrayLists.
|
Object |
put(K key,
Object value)
Adds the value to the collection associated with the specified key.
|
boolean |
putAll(K key,
Collection<V> values)
Adds a collection of values to the collection associated with
the specified key.
|
void |
putAll(Map<? extends K,?> map)
Override superclass to ensure that MultiMap instances are
correctly handled.
|
boolean |
removeMapping(Object key,
Object value)
Removes a specific value from map.
|
int |
size(Object key)
Gets the size of the collection mapped to the specified key.
|
int |
totalSize()
Gets the total size of the map by counting all the values.
|
Collection<Object> |
values()
Gets a collection containing all the values in the map.
|
containsKey, decorated, equals, get, hashCode, isEmpty, keySet, remove, size, toStringmapIteratorclone, finalize, getClass, notify, notifyAll, wait, wait, waitmapIteratorcontainsKey, isEmpty, keySetpublic MultiValueMap()
HashMap and
storing the multiple values in an ArrayList.protected MultiValueMap(Map<K,? super C> map, Factory<C> collectionFactory)
map and
creates the value collections using the supplied collectionFactory.C - the collection class typemap - the map to decoratecollectionFactory - the collection factory which must return a Collection instancepublic static <K,V> MultiValueMap<K,V> multiValueMap(Map<K,? super Collection<V>> map)
K - the key typeV - the value typemap - the map to wrappublic static <K,V,C extends Collection<V>> MultiValueMap<K,V> multiValueMap(Map<K,? super C> map, Class<C> collectionClass)
map and
maps keys to collections of type collectionClass.K - the key typeV - the value typeC - the collection class typemap - the map to wrapcollectionClass - the type of the collection classpublic static <K,V,C extends Collection<V>> MultiValueMap<K,V> multiValueMap(Map<K,? super C> map, Factory<C> collectionFactory)
map and
creates the value collections using the supplied collectionFactory.K - the key typeV - the value typeC - the collection class typemap - the map to decoratecollectionFactory - the collection factory (must return a Collection object).public void clear()
public boolean removeMapping(Object key, Object value)
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, null will be returned
from a subsequent get(key).
removeMapping in interface MultiMap<K,V>key - the key to remove fromvalue - the value to removetrue if the mapping was removed, false otherwisepublic boolean containsValue(Object value)
This checks all collections against all keys for the value, and thus could be slow.
containsValue in interface Map<K,Object>containsValue in interface Get<K,Object>containsValue in interface MultiMap<K,V>containsValue in class AbstractMapDecorator<K,Object>value - the value to search forMap.containsValue(Object)public Object put(K key, Object value)
Unlike a normal Map the previous value is not replaced.
Instead the new value is added to the collection stored against the key.
put in interface Map<K,Object>put in interface MultiMap<K,V>put in interface Put<K,Object>put in class AbstractMapDecorator<K,Object>key - the key to store againstvalue - the value to add to the collection at the keyMap.put(Object, Object)public void putAll(Map<? extends K,?> map)
If you call this method with a normal map, each entry is
added using put(Object,Object).
If you call this method with a multi map, each entry is
added using putAll(Object,Collection).
public Set<Map.Entry<K,Object>> entrySet()
NOTE: the returned Entry objects will contain as value a Collection
of all values that are mapped to the given key. To get a "flattened" version
of all mappings contained in this map, use iterator().
public Collection<Object> values()
This returns a collection containing the combination of values from all keys.
public boolean containsValue(Object key, Object value)
key - the key to search forvalue - the value to search forpublic Collection<V> getCollection(Object key)
get(key).key - the key to retrievepublic int size(Object key)
key - the key to get size forpublic boolean putAll(K key, Collection<V> values)
key - the key to store againstvalues - the values to add to the collection at the key, null ignoredpublic Iterator<V> iterator(Object key)
key - the key to get an iterator forpublic Iterator<Map.Entry<K,V>> iterator()
MultiValueMap.
The iterator will return multiple Entry objects with the same key if there are multiple values mapped to this key.
NOTE: calling Map.Entry.setValue(Object) on any of the returned
elements will result in a UnsupportedOperationException.
public int totalSize()
protected Collection<V> createCollection(int size)
This method can be overridden to perform your own processing instead of using the factory.
size - the collection size that is about to be addedCopyright © 2001–2013 The Apache Software Foundation. All rights reserved.