Class MultiValueMapCollector<T,K,V>

java.lang.Object

org.springframework.util.MultiValueMapCollector<T,K,V>

Type Parameters:

T - the type of input elements to the reduction operation

K - the key type

V - the value element type

All Implemented Interfaces:

Collector<T, MultiValueMap<K,V>, MultiValueMap<K,V>>

public final class MultiValueMapCollector<T,K,V>
extends Object
implements Collector<T, MultiValueMap<K,V>, MultiValueMap<K,V>>

A Collector for building a MultiValueMap from a Stream.

Copied from the Spring Data Commons project.

Since:

7.0.2

Author:

Jens Schauder, Florian Hof, Sam Brannen

Nested Class Summary

Nested classes/interfaces inherited from interface Collector

Collector.Characteristics

Method Summary

Modifier and Type	Method	Description
BiConsumer<MultiValueMap<K,V>, T>	accumulator()
Set<Collector.Characteristics>	characteristics()
BinaryOperator<MultiValueMap<K,V>>	combiner()
Function<MultiValueMap<K,V>, MultiValueMap<K,V>>	finisher()
static <K,V> MultiValueMapCollector<V,K,V>	indexingBy(Function<V,K> indexer)	Create a new MultiValueMapCollector using the given indexer.
static <T,K,V> MultiValueMapCollector<T,K,V>	of(Function<T,K> keyFunction, Function<T,V> valueFunction)	Create a new MultiValueMapCollector from the given key and value functions.
Supplier<MultiValueMap<K,V>>	supplier()

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

of

public static <T,K,V> MultiValueMapCollector<T,K,V> of(Function<T,K> keyFunction,
 Function<T,V> valueFunction)

Create a new MultiValueMapCollector from the given key and value functions.

Type Parameters:

T - the type of input elements to the reduction operation

K - the key type

V - the value element type

Parameters:

keyFunction - a Function which converts an element of type T to a key of type K

valueFunction - a Function which converts an element of type T to an element of type V; supply Function.identity() if no conversion should be performed

Returns:

a new MultiValueMapCollector

See Also:

• indexingBy(Function)

indexingBy

public static <K,V> MultiValueMapCollector<V,K,V> indexingBy(Function<V,K> indexer)

Create a new MultiValueMapCollector using the given indexer.

Delegates to of(Function, Function), supplying the given indexer as the key function and Function.identity() as the value function.

For example, if you would like to collect the elements of a Stream of strings into a MultiValueMap keyed by the lengths of the strings, you could create such a Collector via MultiValueMapCollector.indexingBy(String::length).

Type Parameters:

K - the key type

V - the value element type

Parameters:

indexer - a Function which converts a value of type V to a key of type K

Returns:

a new MultiValueMapCollector based on an indexer

See Also:

• of(Function, Function)

supplier

public Supplier<MultiValueMap<K,V>> supplier()

Specified by:

supplier in interface Collector<T,K,V>

accumulator

public BiConsumer<MultiValueMap<K,V>, T> accumulator()

Specified by:

accumulator in interface Collector<T,K,V>

combiner

public BinaryOperator<MultiValueMap<K,V>> combiner()

Specified by:

combiner in interface Collector<T,K,V>

finisher

public Function<MultiValueMap<K,V>, MultiValueMap<K,V>> finisher()

Specified by:

finisher in interface Collector<T,K,V>

characteristics

public Set<Collector.Characteristics> characteristics()

Specified by:

characteristics in interface Collector<T,K,V>