5

Assuming I've already a reactive stream and now I wanna add one more object to this existing stream. How can I do this?

This is the approach i found, is this the way to go?

import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;

import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxSink;

/**
 * Created by ton on 10/11/16.
 */
public class Example {

    private List<FluxSink<String>> handlers = new ArrayList<>();

    public Flux<String> getMessagesAsStream() {
        Flux<String> result = Flux.create(sink -> {
                handlers.add(sink);
            sink.setCancellation(() -> handlers.remove(sink));
        });

        return result;
    }

    public void handleMessage(String message) {
        handlers.forEach(han -> han.next(message));
    }

    public static void main(String[] args) {
        Example example = new Example();
        example.getMessagesAsStream().subscribe(req -> System.out.println("req = " + req));
        example.getMessagesAsStream().subscribe(msg -> System.out.println(msg.toUpperCase()));
        example.handleMessage("een");
        example.handleMessage("twee");
        example.handleMessage("drie");
    }
}
botscripter
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1 Answers1

9

Suppose this is your existing stream:

Flux<Integer> existingStream = Flux.just(1, 2, 3, 4);

You can concatenate two streams:

Flux<Integer> appendObjectToStream = Flux.concat(existingStream, Flux.just(5));

This will produce [1, 2, 3, 4, 5].

Alternatively you could merge both streams:

Flux<Integer> mergeObjectWithStream = Flux.merge(existingStream, Flux.just(5));

That will produce a similar stream, however the 5 element could appear anywhere in the resulting flux.

systemfreund
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    But this creates a new Flux. What if I want to add objects to Flux already used by some other object ? – Raphaël Lemaire Jun 16 '20 at 14:57
  • You can only 'compose' them as described above. What you want to do is not possible as far as I know. There might be some ways to do it, but I'm sure it's not intended to do so. – systemfreund Jun 17 '20 at 15:11
  • I set up code similar to rhea-0b1's with FluxSink and it seems to be working fine. Is there some problem with this we should be aware of ? – Raphaël Lemaire Jul 01 '20 at 15:38