Apache Commons Collections 4.4 · org.apache.commons.collections4.SetValuedMap

Defines a map that holds a set of values against each key.

A SetValuedMap is a Map with slightly different semantics:

Putting a value into the map will add the value to a Set at that key.
Getting a value will return a Set, holding all the values put to that key.

Method Summary

Modifier and Type	Method and Description
public Set<V>	Returns: the `Set` of values, implementations should return an empty `Set` for no mapping get(K the key to retrieve key) Redeclares org.apache.commons.collections4.MultiValuedMap.get. Gets the set of values associated with the specified key.
public Set<V>	Returns: the `Set` of values removed, implementations should return null for no mapping found, but may return an empty collection remove(Object the key to remove values from key) Redeclares org.apache.commons.collections4.MultiValuedMap.remove. Removes all values associated with the specified key.

Inherited from org.apache.commons.collections4.MultiValuedMap:: asMap clear containsKey containsMapping containsValue entries isEmpty keys keySet mapIterator put putAll putAll putAll removeMapping size values

Method Detail

get back to summary

get	back to summary
public Set<V> get(K key) Redeclares org.apache.commons.collections4.MultiValuedMap.get. Gets the set of values associated with the specified key. Implementations typically return an empty `Set` if no values have been mapped to the key. Parameters key:K the key to retrieve Returns:Set<V> the `Set` of values, implementations should return an empty `Set` for no mapping Annotations @Override Exceptions NullPointerException: if the key is null and null keys are invalid

public Set<V> get(K key)

Redeclares org.apache.commons.collections4.MultiValuedMap.get.

Gets the set of values associated with the specified key.

Implementations typically return an empty Set if no values have been mapped to the key.

Parameters

key:K: the key to retrieve

Returns:Set<V>

the Set of values, implementations should return an empty Set for no mapping

Annotations

@Override

Exceptions

NullPointerException:: if the key is null and null keys are invalid

remove back to summary

remove	back to summary
public Set<V> remove(Object key) Redeclares org.apache.commons.collections4.MultiValuedMap.remove. Removes all values associated with the specified key. The returned set may be modifiable, but updates will not be propagated to this set-valued map. In case no mapping was stored for the specified key, an empty, unmodifiable set will be returned. Parameters key:Object the key to remove values from Returns:Set<V> the `Set` of values removed, implementations should return null for no mapping found, but may return an empty collection Annotations @Override Exceptions UnsupportedOperationException: if the map is unmodifiable NullPointerException: if the key is null and null keys are invalid

public Set<V> remove(Object key)

Redeclares org.apache.commons.collections4.MultiValuedMap.remove.

Removes all values associated with the specified key.

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