MainActivity.this call, in Fragment

Question

I'm new in android. I have a code which is consisted ViewPager and TabLayout. And it has 4 Fragments. On my Fragment4 code, I want to use CircleProgressView which I got in GitHub. To use that code, I should use AsyncTask. And it has "MainActivity.this.runOnUiThread(new Runnable){}". But this code occurred error. The message is "MainActivity is not an enclosing class." I think it means MainActivity class could not be referred. How can I call "MainActivity.this.runOnUiThread()"? Please tell me how to fix code.

Here is a part of my code.

public class Fragment4 extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
    ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.fragment4, container, false);

    ...

    return rootView;

    }

    @Override
    public void onStart() {
        super.onStart();
    }

    private class LongOperation extends AsyncTask<Void, Void, Void> {
        @Override
        protected Void doInBackground(Void... params) {

            MainActivity.this.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mCircleView.setValue(0);
                    mCircleView.spin();
                }
            });

            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            mCircleView.setValueAnimated(42);
        }
    }
}

Answer 1

Use getActivity() instead of MainActivity.this

 getActivity().runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    mCircleView.setValue(0);
                    mCircleView.spin();
                }
            });