RxAndroid问题与改造？

Question

I'm having a cast problem inside the subscribe method, i don't know why the new Observer is giving this issue.

 Observable<GradeModel> getGrade = retrofit
                .create(GradeService.class)
                .getGrade()
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .map(model -> {
                    // transform model
                    DecimalFormat grades = (DecimalFormat) model.getGrades();
                    return grades;
                })
                .subscribe(new Subscriber<DecimalFormat>() {
                    @Override
                    public void onCompleted() {

                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.i(TAG, "onError method of observer");
                    }

                    @Override
                    public void onNext(DecimalFormat grades) {
                        mainPresenter.setListGrades(grades);
                    }
                });

Required: rx.Observable Found: rx.Subscription

Answer 1

Up until .subscribe(...) it is an Observable . However after subscribing it returns a Subscription instance which can be used to cancel the subscription.

The exception occurs because you are casting this Subscription back into an Observable although they are completely unrelated.

Without knowing your intentions with that variable it is hard to say what the correct code would be.