Package org.kiwiproject.collect

Class KiwiCollectors

java.lang.Object

org.kiwiproject.collect.KiwiCollectors

public class KiwiCollectors
extends Object

Utility for custom Collector implementations

Constructor Summary

Constructors

Constructor	Description
KiwiCollectors()

Method Summary

Modifier and Type	Method	Description
static <T,K extends Enum<K>,U> Collector<T,?,Map<K,U>>	toEnumMap(Class<K> enumClass, Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper)	Returns a Collector that collects into an EnumMap.
static <E extends Enum<E>> Collector<E,EnumSet<E>,EnumSet<E>>	toEnumSet(Class<E> type)	Returns a Collector that collects into an EnumSet.
static <T> Collector<T,com.google.common.collect.ImmutableList.Builder<T>,com.google.common.collect.ImmutableList.Builder<T>>	toImmutableListBuilder()	Return a Collector that collects into a Guava ImmutableList.Builder.
static <T,K,U> Collector<T,?,Map<K,U>>	toLinkedMap(Function<? super T,? extends K> keyMapper, Function<? super T,? extends U> valueMapper)	Returns a Collector that collects intoa LinkedHashMap.

Methods inherited from class java.lang.Object

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

Constructor Detail

KiwiCollectors

public KiwiCollectors()

Method Detail

toImmutableListBuilder

public static <T> Collector<T,com.google.common.collect.ImmutableList.Builder<T>,com.google.common.collect.ImmutableList.Builder<T>> toImmutableListBuilder()

Return a Collector that collects into a Guava ImmutableList.Builder. You only then need to call ImmutableList.Builder.build().

Type Parameters:

T - the type in the list

Returns:

ImmutableList of T

toEnumSet

public static <E extends Enum<E>> Collector<E,EnumSet<E>,EnumSet<E>> toEnumSet(Class<E> type)

Returns a Collector that collects into an EnumSet.

Type Parameters:

E - the enum type subclass

Parameters:

type - the type in the EnumSet

Returns:

the Collector

toEnumMap

public static <T,K extends Enum<K>,U> Collector<T,?,Map<K,U>> toEnumMap(Class<K> enumClass,
                                                                                                      Function<? super T,? extends K> keyMapper,
                                                                                                      Function<? super T,? extends U> valueMapper)

Returns a Collector that collects into an EnumMap.

If the mapped keys contain duplicates (according to Object.equals(Object), an IllegalStateException is thrown when the collection operation is performed.

Type Parameters:

T - the type of the input elements

K - the output type of the key mapping function

U - the outptu type of the value mapping function

Parameters:

enumClass - the key type for the returned map

keyMapper - a mapping function to produce keys

valueMapper - a mapping function to produce values

Returns:

a Collector which collects elements into an EnumMap whose keys are the result of applying key and value mapping functions.

toLinkedMap

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

Returns a Collector that collects intoa LinkedHashMap.

Type Parameters:

T - the type of the input elements

K - the output type of the key mapping function

U - the output type of the value mapping function

Parameters:

keyMapper - a mapping function to produce keys

valueMapper - a mapping function to produce values

Returns:

a Collector which collects elements into a LinkedHashMap whose keys are the result of applying key and value mapping functions.