Source.single

Stream a single object once.

Source operators

Signature

Source.singleSource.single

Description

Stream a single object once and complete after thereafter.

See also:

  • repeat Stream a single object repeatedly.
  • tick A periodical repetition of an arbitrary object.
  • cycle Stream iterator in cycled manner.

Examples

Scala
import akka.stream._

val s: Future[immutable.Seq[Int]] = Source.single(1).runWith(Sink.seq)
s.foreach(list => println(s"Collected elements: $list")) // prints: Collected elements: List(1)
Java
import akka.stream.*;

CompletionStage<List<String>> future = Source.single("A").runWith(Sink.seq(), system);
CompletableFuture<List<String>> completableFuture = future.toCompletableFuture();
completableFuture.thenAccept(result -> System.out.printf("collected elements: %s\n", result));
// result list will contain exactly one element "A"

Reactive Streams semantics

emits the value once

completes when the single value has been emitted

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