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

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

A ListValuedMap is a Map with slightly different semantics:

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

Method Summary

Modifier and Type	Method and Description
public List<V>	Returns: the `List` of values, implementations should return an empty `List` for no mapping get(K the key to retrieve key) Redeclares org.apache.commons.collections4.MultiValuedMap.get. Gets the list of values associated with the specified key.
public List<V>	Returns: the `List` of values removed, implementations typically return an empty, unmodifiable `List` for no mapping found 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 List<V> get(K key) Redeclares org.apache.commons.collections4.MultiValuedMap.get. Gets the list of values associated with the specified key. This method will return an empty list if `containsKey(Object)` returns `false`. Changes to the returned list will update the underlying `ListValuedMap` and vice-versa. Parameters key:K the key to retrieve Returns:List<V> the `List` of values, implementations should return an empty `List` for no mapping Annotations @Override Exceptions NullPointerException: if the key is null and null keys are invalid

public List<V> get(K key)

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

Gets the list of values associated with the specified key.

This method will return an empty list if containsKey(Object) returns false. Changes to the returned list will update the underlying ListValuedMap and vice-versa.

Parameters

key:K: the key to retrieve

Returns:List<V>

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

public List<V> remove(Object key)

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

Removes all values associated with the specified key.

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