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
StreamConverters
StreamConverters
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 Akka 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 Sink
Sink
that materializes into a java.util.stream.Stream
.
- Scala
-
source
import java.util.stream import java.util.stream.IntStream import akka.NotUsed import akka.stream.scaladsl.Keep import akka.stream.scaladsl.Sink import akka.stream.scaladsl.Source import akka.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)
- Java
-
source
import akka.japi.function.Creator; import akka.stream.Materializer; import akka.stream.javadsl.Sink; import akka.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
cancels when the Java Stream is closed
backpressures when no read is pending on the Java Stream