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

Java

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

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¶