Sink.none

A Sink that will test the given predicate p for every received element and completes with the result.

Sink operators

Signature¶

Sink.noneSink.none

Description¶

none operator applies a predicate function to assert each element received, it returns false if any element satisfy the assertion, otherwise it returns true.

It materializes into a Future (in Scala) or a CompletionStage (in Java) that completes with the last state when the stream has finished.

Notes that if source is empty, it will return true

A Sink that will test the given predicate p for every received element and

• completes and returns Future CompletionStage of true if the predicate is false for all elements;
• completes and returns Future CompletionStage of true if the stream is empty (i.e. completes before signalling any elements);
• completes and returns Future CompletionStage of false if the predicate is true for any element.

The materialized value Future CompletionStage will be completed with the value true or false when the input stream ends, or completed with Failure if there is a failure signaled in the stream.

Example¶

This example tests all elements in the stream is <= 100.

Scala

Java

copysourceval result: Future[Boolean] =
  Source(1 to 100)
    .runWith(Sink.none(_ > 100))
val noneMatch = Await.result(result, 3.seconds)
println(noneMatch)
// Expect prints:
// true

copysourcefinal boolean noneMatch =
    Source.range(1, 100)
        .runWith(Sink.none(elem -> elem > 100), system)
        .toCompletableFuture()
        .get(3, TimeUnit.SECONDS);
System.out.println(noneMatch);
// Expect prints:
// true

Reactive Streams Semantics¶