parallel promises example

ParallelPromises.java

Promise<ResponseTypeA> responseA;
Promise<ResponseTypeB> responseB;

p1.then(new PromiseAction<A>() {
  public void call(A response) {
    // do something with the response
  }
});

p2.then(new PromiseAction<B>() {
  public void call(B value) {
    // do something with the response
  }
});

p1.and(p2).then(new PromiseAction<A, B>) {
  public void call(A responseA, B responseB) {
    // compute something that needs both values
  }
}