What is the ideal way to handle two different types of futures where one future is dependent on the other future?

I'm looking at AKKA's Java Futures API, and I see a lot of ways to handle multiple futures of the same type, but I don't see anything that pops out at me for handling futures of different types. I开发者_如何学JAVA'm guessing that I'm making this more complicated than it is.

Anyways let's say we have two different Actors: actorA and actorB. They are based on different classes and they each return a different Future. However, actorB is dependent on a Future from actorA. Is the following logic, how to best handle this case?

Future<A> a = actorA.sendRequestReplyFuture(...);

Future<B> b = actorB.sendRequestReplyFuture(a);

How about if we have a list of actorAs and actorBs?

WARNING, just written from memory, might not compile OOTB:

Future<B> b = actor.sendRequestReplyFuture().flatMap( new akka.japi.Function<A,Future<B>>() {
  public Future<B> apply(A a) {
     return actor.sendRequestReplyFuture(a);
  }
}

Why not just wrap them, as you have, but with one slight change - pass the result of a into b.

Future a = actorA.sendRequestReplyFuture(...);

Future b = actorB.sendRequestReplyFuture(a.get());

This arrangement just means that actorB.sendRequestReplyFuture() won't get called until actorA.sendRequestReplyFuture() has finished. Nothing wrong with that, in fact, I like the pattern you've got there.