collectWhile

Transform this stream by applying the given partial function to each of the elements on which the function is defined as they pass through this processing step, and cancel the upstream publisher after the partial function is not applied.

Simple operators

Signature

Source.collectWhileSource.collectWhile Flow.collectWhileFlow.collectWhile

Description

Transform this stream by applying the given partial function to each of the elements on which the function is defined as they pass through this processing step, and cancel the upstream publisher after the partial function is not applied.

Example

Scala

copysourceFlow[Message].collectWhile {
  case Ping(id) if id <= 100 => Pong(id)
}

Java

copysourceFlow<Message, Pong, NotUsed> flow =
    Flow.of(Message.class)
        .collectWhile(
            PFBuilder.<Message, Pong>create()
                .match(Ping.class, p -> p.id <= 100, p -> new Pong(p.id))
                .build());

Reactive Streams semantics