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I want to implement a logic using RxJava in my android application, which requires three parallel api calls. Only the third api call has a retry logic. If, after having three attempts, the success is achieved then a subsequent call will be made for the fourth api, else only the result of first and second api calls will be passed on to the subscriber.

I tried to achieve this using Zip operator but then got stuck with retry logic for third api call. 

    Observable<String> observable1 = Observable.just("A","B");

    Observable<Integer> observable2 = Observable.just(1,2);

    Observable<Boolean> observable3 = Observable.just(Boolean.TRUE,     Boolean.FALSE);

Observable.zip(observable1, observable2, observable3, new Function3() { @Override public Object apply(String s, Integer integer, Boolean aBoolean) throws Exception { if (aBoolean==null){ alphabets3.retry(3).doOnComplete(new Action() { @Override public void run() throws Exception { // the result will never be used } }); }

            return s+integer+aBoolean;
        }
    }).subscribe(new Observer<Object>() {
        @Override
        public void onSubscribe(Disposable d) {

        }

        @Override
        public void onNext(Object o) {
            Log.e("onNext-->", o.toString());
        }

        @Override
        public void onError(Throwable e) {

        }

        @Override
        public void onComplete() {

        }
    });
Android1005
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1 Answers1

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if any Observable failed in the Zip operator, Zip will fail the stream, the only way I know to achieve parallel execution and error handling with Zip, is to add onErrorResumeNext to each Observable, that map the error to a new model to deal with later .. and handling what you want to do in the zip mapping function ... for example

Obsevable.zip(
observable1.onErrorResumeNext{Observable.just(Model(it)},
observable2.onErrorResumeNext{Observable.just(Model(it)},
observable3.retryWhen {t is TimeOutException} //here you can add your retry logic
.onErrorResumeNext(t -> Observable.just(Model(t)),(m1 , m2, m3) -> Result())
Mohamed Ibrahim
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  • Hi, the solution suggested by you is having one issue. Zip operator will not pass the result of first and second observable if the third observable is failing in its response. So, what I want is, irrespective of the result of any observable, the other observables should be able to send their result to onNext of subscriber method. How shall I achieve this? – Android1005 Jun 03 '19 at 13:19
  • yes that's why there's the retry and onErrorResumeNext on the third ... so you retry in one kind of error and consume others with onErrorResumeNext so it doesn't break the stream – Mohamed Ibrahim Jun 03 '19 at 15:14
  • you can pass your code, and I'll give it a try on my machine @Android1005 – Mohamed Ibrahim Jun 03 '19 at 15:15