er.extensions.stream

Class ERXCollectors

java.lang.Object

er.extensions.stream.ERXCollectors

public class ERXCollectors
extends Object

Implementations of Collector that implement various useful reduction operations related with NSCollection classes.

The following are examples of using the predefined collectors to perform common mutable reduction tasks:

 // Accumulate names into a NSArray
 NSArray array = people.stream().map(Person::name).collect(ERXCollectors.toNSArray());

 // Accumulate names into a NSSet
 NSSet set = people.stream().map(Person::name).collect(ERXCollectors.toNSSet());

 // Accumulate people by name into a NSDictionary
 NSDictionary dictionary = people.stream().collect(ERXCollectors.toNSDictionary(Person::name, Function.identity()));
 

Since:

7.1

Author:

Henrique Prange

Method Summary

Modifier and Type	Method and Description
static <T> Collector<T,?,NSArray<T>>	toNSArray() Returns a Collector that accumulates the input elements into a new NSArray.
static <T,K,U> Collector<T,?,NSDictionary<K,U>>	toNSDictionary(Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper) Returns a Collector that accumulates the input elements grouped by key/value into a new NSDictionary.
static <T,K,U> Collector<T,?,NSDictionary<K,U>>	toNSDictionary(Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper, BinaryOperator<U> mergeFunction) Returns a Collector that accumulates the input elements grouped by key/value into a new NSDictionary.
static <T> Collector<T,?,NSSet<T>>	toNSSet() Returns a Collector that accumulates the input elements into a new NSSet.

Methods inherited from class java.lang.Object

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

Method Detail

toNSArray

public static <T> Collector<T,?,NSArray<T>> toNSArray()

Returns a Collector that accumulates the input elements into a new NSArray.

Type Parameters:

T - the type of the input elements

Returns:

a Collector which collects all the input elements into a NSArray, in encounter order

toNSSet

public static <T> Collector<T,?,NSSet<T>> toNSSet()

Returns a Collector that accumulates the input elements into a new NSSet.

Type Parameters:

T - the type of the input elements

Returns:

a Collector which collects all the input elements into a NSSet, in encounter order

toNSDictionary

public static <T,K,U> Collector<T,?,NSDictionary<K,U>> toNSDictionary(Function<? super T,? extends K> keyMapper,
                                                                      Function<? super T,? extends U> valueMapper)

Returns a Collector that accumulates the input elements grouped by key/value into a new NSDictionary.

Parameters:

keyMapper - a mapping function to produce keys.

valueMapper - a mapping function to produce values.

Returns:

a Collector which collects elements into a NSDictionary whose keys and values are the result of applying mapping functions to the input elements.

toNSDictionary

public static <T,K,U> Collector<T,?,NSDictionary<K,U>> toNSDictionary(Function<? super T,? extends K> keyMapper,
                                                                      Function<? super T,? extends U> valueMapper,
                                                                      BinaryOperator<U> mergeFunction)

Returns a Collector that accumulates the input elements grouped by key/value into a new NSDictionary.

Parameters:

keyMapper - a mapping function to produce keys.

valueMapper - a mapping function to produce values

mergeFunction - a merge function, used to resolve collisions between values associated with the same key, as supplied to Map.merge(Object, Object, BiFunction)

Returns:

a Collector which collects elements into a NSDictionary whose keys are the result of applying a key mapping function to the input elements, and whose values are the result of applying a value mapping function to all input elements equal to the key and combining them using the merge function