StreamConverters.asJavaStream

Create a sink which materializes into Java 8 Stream that can be run to trigger demand through the sink.

Additional Sink and Source converters

Signature¶

StreamConvertersStreamConverters

Description¶

Create a sink which materializes into Java 8 Stream that can be run to trigger demand through the sink. Elements emitted through the stream will be available for reading through the Java 8 Stream.

The Java 8 Stream will be ended when the stream flowing into this Sink completes, and closing the Java Stream will cancel the inflow of this Sink. If the Java Stream throws an exception, the Pekko stream is cancelled.

Be aware that Java Stream blocks current thread while waiting on next element from downstream.

Example¶

Here is an example of a SinkSink that materializes into a java.util.stream.Stream.

Scala

Java

copysourceimport java.util.stream
import java.util.stream.IntStream

import org.apache.pekko
import pekko.NotUsed
import pekko.stream.scaladsl.Keep
import pekko.stream.scaladsl.Sink
import pekko.stream.scaladsl.Source
import pekko.stream.scaladsl.StreamConverters
val source: Source[Int, NotUsed] = Source(0 to 9).filter(_ % 2 == 0)

val sink: Sink[Int, stream.Stream[Int]] = StreamConverters.asJavaStream[Int]()

val jStream: java.util.stream.Stream[Int] = source.runWith(sink)

copysourceimport org.apache.pekko.japi.function.Creator;
import org.apache.pekko.stream.Materializer;
import org.apache.pekko.stream.javadsl.Sink;
import org.apache.pekko.stream.javadsl.StreamConverters;

import java.util.concurrent.CompletionStage;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.stream.BaseStream;
import java.util.stream.IntStream;
import java.util.stream.Stream;

Source<Integer, NotUsed> source = Source.range(0, 9).filter(i -> i % 2 == 0);

Sink<Integer, java.util.stream.Stream<Integer>> sink = StreamConverters.<Integer>asJavaStream();

Stream<Integer> jStream = source.runWith(sink, system);

Reactive Streams semantics¶