How to combine multiple RxJava chains non-blocking in error case

Question

My requirements:

• N Retrofit calls in parallel
• Wait for all calls to finish (success or failure)
• If k (0<= k < N) calls fail, they sho

Answer 1

I think in your use case Zip operator it´s more suitable

Here you can see running in the main thread, but also it´s possible make it run every one of them in another thread if you use observerOn

/**
 * Since every observable into the zip is created to subscribeOn a different thread, it´s means all of them will run in parallel.
 * By default Rx is not async, only if you explicitly use subscribeOn.
  */
@Test
public void testAsyncZip() {
    scheduler = Schedulers.newThread();
    scheduler1 = Schedulers.newThread();
    scheduler2 = Schedulers.newThread();
    long start = System.currentTimeMillis();
    Observable.zip(obAsyncString(), obAsyncString1(), obAsyncString2(), (s, s2, s3) -> s.concat(s2)
                                                                                        .concat(s3))
              .subscribe(result -> showResult("Async in:", start, result));
}



private Observable obAsyncString() {
    return Observable.just("")
                     .observeOn(scheduler)
                     .doOnNext(val -> {
                         System.out.println("Thread " + Thread.currentThread()
                                                              .getName());
                     })
                     .map(val -> "Hello");
}

private Observable obAsyncString1() {
    return Observable.just("")
                     .observeOn(scheduler1)
                     .doOnNext(val -> {
                         System.out.println("Thread " + Thread.currentThread()
                                                              .getName());
                     })
                     .map(val -> " World");
}

private Observable obAsyncString2() {
    return Observable.just("")
                     .observeOn(scheduler2)
                     .doOnNext(val -> {
                         System.out.println("Thread " + Thread.currentThread()
                                                              .getName());
                     })
                     .map(val -> "!");
}

You can see more examples here https://github.com/politrons/reactive