Package no.digipost.stream

Interface EmptyResultIfEmptySourceCollector<T,A,R>

Type Parameters:

T - the type of input elements to the reduction operation

R - the type of value contained in the resulting Optional, if not source is empty.

All Superinterfaces:

Collector<T,A,Optional<R>>

All Known Implementing Classes:

EnforceAtMostOneElementCollector

public interface EmptyResultIfEmptySourceCollector<T,A,R>
extends Collector<T,A,Optional<R>>

A collector type specific for implementations which produce an Optional based on if the source (typically a Stream, or more apropriately, a NonEmptyStream) yields no elements or any element(s). Typically appropriate for reduction operations which needs at least one element to produce a valid result.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.stream.Collector

Collector.Characteristics

Method Summary

Static Methods

Modifier and Type	Method	Description
static <T, A, R> EmptyResultIfEmptySourceCollector<T,A,R>	from(Collector<T,A,Optional<R>> collector)

Methods inherited from interface java.util.stream.Collector

accumulator, characteristics, combiner, finisher, supplier

Method Details

from

static <T,
A,
R>
EmptyResultIfEmptySourceCollector<T,A,R> from(Collector<T,A,Optional<R>> collector)