Package org.kiwiproject.collect

Class KiwiCollectors

java.lang.Object

org.kiwiproject.collect.KiwiCollectors

public final class KiwiCollectors
extends Object

Utility for custom Collector implementations

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

Method Details

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.