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java.lang.Objectorg.apache.commons.collections4.map.AbstractIterableMap<K,V>
org.apache.commons.collections4.map.AbstractMapDecorator<K,Object>
org.apache.commons.collections4.map.MultiValueMap<K,V>
public class MultiValueMap<K,V>
A MultiValueMap decorates another map, allowing it to have more than one value for a key.
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.
Nested Class Summary |
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Nested classes/interfaces inherited from interface java.util.Map |
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Map.Entry<K,V> |
Constructor Summary | |
---|---|
|
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 . |
Method Summary | ||
---|---|---|
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
|
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
|
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
|
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. |
|
V |
remove(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. |
Methods inherited from class org.apache.commons.collections4.map.AbstractMapDecorator |
---|
containsKey, decorated, equals, get, hashCode, isEmpty, keySet, remove, size, toString |
Methods inherited from class org.apache.commons.collections4.map.AbstractIterableMap |
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mapIterator |
Methods inherited from class java.lang.Object |
---|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface org.apache.commons.collections4.MultiMap |
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get, remove, size |
Methods inherited from interface java.util.Map |
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containsKey, equals, hashCode, isEmpty, keySet |
Methods inherited from interface org.apache.commons.collections4.IterableGet |
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mapIterator |
Methods inherited from interface org.apache.commons.collections4.Get |
---|
containsKey, isEmpty, keySet |
Constructor Detail |
---|
public 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 instanceMethod Detail |
---|
public static <K,V> MultiValueMap<K,V> multiValueMap(Map<K,? super Collection<V>> map)
K
- the key typeV
- the value typemap
- the map to wrap
public 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 class
public 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()
clear
in interface Map<K,Object>
clear
in interface Put<K,Object>
clear
in class AbstractMapDecorator<K,Object>
Map.clear()
public V remove(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)
.
remove
in interface MultiMap<K,V>
key
- the key to remove fromvalue
- the value to remove
public 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 for
Map.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 key
Map.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)
.
putAll
in interface Map<K,Object>
putAll
in interface Put<K,Object>
putAll
in class AbstractMapDecorator<K,Object>
map
- the map to copy (either a normal or multi map)Map.putAll(Map)
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()
.
entrySet
in interface Map<K,Object>
entrySet
in interface Get<K,Object>
entrySet
in class AbstractMapDecorator<K,Object>
iterator()
public Collection<Object> values()
This returns a collection containing the combination of values from all keys.
values
in interface Map<K,Object>
values
in interface Get<K,Object>
values
in interface MultiMap<K,V>
values
in class AbstractMapDecorator<K,Object>
Map.values()
public boolean containsValue(Object key, Object value)
key
- the key to search forvalue
- the value to search for
public Collection<V> getCollection(Object key)
get(key)
.
key
- the key to retrieve
public int size(Object key)
key
- the key to get size for
public boolean putAll(K key, Collection<V> values)
key
- the key to store againstvalues
- the values to add to the collection at the key, null ignored
public Iterator<V> iterator(Object key)
key
- the key to get an iterator for
public 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 added
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