CODEWITHSUNDEEP
javarx-javarx-java2
jeremy303
jeremy303

Reputation: 9241

Only catch exceptions of a specific type in RxJava 2

I'm just learning RxJava 2 and I would like catch exceptions only of a specific type and return an Observable. Essentially, I want onErrorResumeNext() to only catch a specific exception class, but it looks like she doesn't work that way.

What are my options for achieving this behavior in RxJava 2? Just use onErrorResumeNext(), handle my specific exception and rethrow the others? Something like:

.onErrorResumeNext(throwable -> throwable instanceof NotFoundException ? Observable.empty() : Observable.error(throwable));

Upvotes: 6

Views: 6323

Answers (3)

Lukas
Lukas

Reputation: 1215

if you need global error handling, you can use RxJavaPlugins

RxJavaPlugins.setOnObservableAssembly(observable -> {
        if (observable instanceof ObservableError){
            return observable.doOnError(throwable -> {
                if(throwable instanceof SpecificException){
                    handleSpecificException();
                }
            });
        }
        return observable;
    });

(Similar approach can be used for Singles, Maybes or Completables)

Upvotes: 1

paul
paul

Reputation: 13471

I would return Observable.empty instead just null

.onErrorResumeNext(t -> t instanceof NullPointerException ? Observable.empty():Observable.error(t))

Upvotes: 7

Tassos Bassoukos
Tassos Bassoukos

Reputation: 16152

Just use composition:

public <T> Function<Throwable, Observable<T>> whenExceptionIsThenIgnore(Class<E> what) {
  return t -> {
    return what.isInstance(t) ? Observable.empty() : Observable.error(t);
  };
}

Then use like this:

Observable.from(...).flatMap(...)
.onErrorResumeNext(whenExceptionIsThenIgnore(IllegalArgumentException.class))
.onErrorResumeNext(whenExceptionIsThenIgnore(IOException.class))
...

See also this answer on selectively handling exceptions.

Upvotes: 6

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