rxjava - How to handle merge exceptions without terminating the whole process - exception

Question

I have created two observables.
One of them throws an exception.
obs1 = Observable.from(new Integer[]{1, 2, 3, 4, 5, 6});
obs2 = Observable.create(new Observable.OnSubscribe<Integer>() {
#Override public void call(Subscriber<? super Integer> subscriber) {
boolean b = getObj().equals(""); // this throws an exception
System.out.println("1");
}
});
Now I invoke them using
Observable.merge(obs2, obs1)
.subscribe(new Observer<Integer>() {
#Override public void onCompleted() {
System.out.println("onCompleted");
}
#Override public void onError(Throwable throwable) {
System.out.println("onError");
}
#Override public void onNext(Integer integer) {
System.out.println("onNext - " + integer);
}
});
Now, I dont want my process to halt completely when an exception occurs -
I want to handle it and I want obs1 to continue its work.
I have tried to write it using onErrorResumeNext(), onExceptionResumeNext(), doOnError()
but nothing helped - obs1 did not run.
How can I handle the exception without stopping the other observable from being processed?

Answer 1

Sounds like you need mergeDelayError.

Answer 2

The problem is in your subscriber which is broken. You should catch your exception and call onError. Otherwise, you broke the rx contract.
example :
Observable<Integer> obs1 = Observable.from(Arrays.asList(1, 2, 3, 4, 5, 6));
Observable<Integer> obs2 = Observable.create((Subscriber<? super Integer> subscriber) -> {
subscriber.onError(new NullPointerException());
});
Observable.merge(obs2.onErrorResumeNext((e) -> Observable.empty()), obs1)
.subscribe(new Observer<Integer>() {
#Override public void onCompleted() {
System.out.println("onCompleted");
}
#Override public void onError(Throwable throwable) {
System.out.println("onError");
}
#Override public void onNext(Integer integer) {
System.out.println("onNext - " + integer);
}
});
so if you replace your obs2 code with this, it should work like you expected :
obs2 = Observable.create(new Observable.OnSubscribe<Integer>() {
#Override public void call(Subscriber<? super Integer> subscriber) {
try {
boolean b = getObj().equals(""); // this throws an exception
System.out.println("1");
} catch(Exception ex) {
subscriber.onError(ex);
}
}
});