Observable.create(new ObservableOnSubscribe<Integer>() {
    @Override
    public void subscribe(ObservableEmitter<Integer> e) throws Exception {
        e.onNext(1);
        e.onNext(2);
        e.onError(new Throwable("Error occurred"));
    }
}).onErrorResumeNext(new Function<Throwable, ObservableSource<? extends Integer>>() {
    @Override
    public ObservableSource<? extends Integer> apply(@NonNull Throwable throwable) throws Exce
        Log.d(TAG, "apply e=" + throwable.getMessage());
        return Observable.just(3, 4);
    }
}).subscribe(new Observer<Integer>() {
    @Override
    public void onSubscribe(Disposable d) {
        Log.d(TAG, "onSubscribe");
    }
    @Override
    public void onNext(Integer value) {
        Log.d(TAG, "onNext value=" + value);
    }
    @Override
    public void onError(Throwable e) {
        Log.d(TAG, "onError e=" + e.getMessage());
    }
    @Override
    public void onComplete() {
        Log.d(TAG, "onComplete");
    }
});