SetValuedMap (Apache Commons Collections 4.2 API)

Type Parameters:

K - the type of the keys in this map

V - the type of the values in this map

All Superinterfaces:

MultiValuedMap<K,V>

All Known Implementing Classes:

AbstractSetValuedMap, HashSetValuedHashMap
```
public interface SetValuedMap<K,V>
extends MultiValuedMap<K,V>
```
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.
Since:

4.1

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Set<V>`	`get(K key)`	Gets the set of values associated with the specified key.
`Set<V>`	`remove(Object key)`	Removes all values associated with the specified key.

Methods inherited from interface 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
```
Set<V> get(K key)
```
    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.
    
    Specified by:
    
    get in interface MultiValuedMap<K,V>
    
    Parameters:
    
    key - the key to retrieve
    
    Returns:
    
    the Set of values, implementations should return an empty Set for no mapping
    
    Throws:
    
    NullPointerException - if the key is null and null keys are invalid
  - remove
```
Set<V> remove(Object key)
```
    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.
    
    Specified by:
    
    remove in interface MultiValuedMap<K,V>
    
    Parameters:
    
    key - the key to remove values from
    
    Returns:
    
    the Set of values removed, implementations should return null for no mapping found, but may return an empty collection
    
    Throws:
    
    UnsupportedOperationException - if the map is unmodifiable
    
    NullPointerException - if the key is null and null keys are invalid