Observable.create is not recommended to use. as your own example states

//Java
Observable.create(new Observable.OnSubscribe<Integer>() {
    @Override
    public void call(final Subscriber<? super Integer> 
subscriber) {
        for (int i = 1; i <= 5; i++)
            subscriber.onNext(i);

        subscriber.onCompleted();
    }
});

and it should be

//Java
Observable.create(new Observable.OnSubscribe<Integer>() {
    @Override
    public void call(final Subscriber<? super Integer> 
subscriber) { if(!subscriber.isUnsubscribed) {      for (int i = 1; i <= 5; i++)
            subscriber.onNext(i);

        subscriber.onCompleted();}    }
});

keep in mind that this can be a source of lot of headache. And if you use .create please remember to add check for subscriber