How to access actors from receptionist in non-actor classes using Akka Java?

Question

I have different actors running as part of Akka systems having different types. How can I find an actor from non-actor class having System object using receptionist. I don't have direct reference or any way to pass the reference to non-actor class.

Answer 1

Thankfully I could come up with generic and elegant solution using Java AKKA and Receptionist !!

private <T> CompletableFuture<ActorRef<T>> findActor(ActorSystem<Void> system, ServiceKey<T> actorKey) {
    ActorRef<Command> receptionist = system.receptionist();
    Duration askTimeout = Duration.ofSeconds(3);
    CompletionStage<Listing> result = AskPattern.ask(
            receptionist,
            replyTo -> Receptionist.find(actorKey, replyTo),
            askTimeout,
            system.scheduler());

    return result.toCompletableFuture().thenApplyAsync(
            (reply) -> {
                if (reply != null && reply instanceof Listing) {
                    return reply.getServiceInstances(actorKey).stream().findFirst().get();
                }
                return null;
            }).exceptionally((Throwable ex) -> {
                return null;
            });
}