Package dev.bannmann.labs.core

Class StreamExtras

java.lang.Object

dev.bannmann.labs.core.StreamExtras

public final class StreamExtras
extends Object

Method Summary

Modifier and Type	Method	Description
static <T extends @Nullable Object> BinaryOperator<T>	atMostOne()	Use with Stream.reduce(BinaryOperator) to ensure there is at most one element.
static <T extends @Nullable Object, E extends RuntimeException> BinaryOperator<T>	atMostOneThrowing(Supplier<E> exception)	Use with Stream.reduce(BinaryOperator) to ensure there is at most one element.
static <T> Collector<T,?,List<T>>	lastN(int limit)	Collects the last n input elements (or fewer) into a list.

Methods inherited from class java.lang.Object

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

Method Details

atMostOne

public static <T extends @Nullable Object>
BinaryOperator<T> atMostOne()

Use with Stream.reduce(BinaryOperator) to ensure there is at most one element. Note that if you want an exception in case no element exists, you should instead use Guava's MoreCollectors.onlyElement().

Type Parameters:

T - element type

Returns:

an operator to use with Stream.reduce(BinaryOperator)

atMostOneThrowing

public static <T extends @Nullable Object,
E extends RuntimeException>
BinaryOperator<T> atMostOneThrowing(Supplier<E> exception)

Use with Stream.reduce(BinaryOperator) to ensure there is at most one element. Note that if you want an exception in case no element exists, you should instead use Guava's MoreCollectors.onlyElement().

Type Parameters:

T - element type

E - type of the exception to throw if more than one element is encountered

Parameters:

exception - thrown if more than one element is encountered

lastN

public static <T> Collector<T,?,List<T>> lastN(int limit)

Collects the last n input elements (or fewer) into a list.

Type Parameters:

T - element type

Parameters:

limit - the maximum number of elements. Must be greater than 0.

Throws:

IllegalArgumentException - if limit is 0 or negative