RXJava2: correct pattern to chain retrofit requests

Question

I am relatively new to RXJava in general (really only started using it with RXJava2), and most documentation I can find tends to be RXJava1; I can usually translate between

Answer 1

I would suggest using flat map (And retrolambda if that is an option). Also you do not need to keep the return value (e.g Single first) if you are not doing anything with it.

retrofitService.getSomething()
    .flatMap(firstResponse -> retrofitService.getSecondResponse(firstResponse.id)
    .subscribeWith(new DisposableSingleObserver() {
         @Override
         public void onSuccess(final SecondResponse secondResponse) {
            // we're done with both!
         }

         @Override
          public void onError(final Throwable error) {
             // a request request Failed, 
          }                        
   });

This article helped me think through styles in how I structure RxJava in general. You want your chain to be a list of high level actions if possible so it can be read as a sequence of actions/transformations.

EDIT Without lambdas you can just use a Func1 for your flatMap. Does the same thing just a lot more boiler-plate code.

retrofitService.getSomething()
    .flatMap(new Func1 {
        public void Observable call(FirstResponse firstResponse) {
            return retrofitService.getSecondResponse(firstResponse.id)
        }
    })
    .subscribeWith(new DisposableSingleObserver() {
         @Override
         public void onSuccess(final SecondResponse secondResponse) {
            // we're done with both!
         }

         @Override
          public void onError(final Throwable error) {
             // a request request Failed, 
          }                        
   });