Animation start/stop within AsyncTask

Question

I need to start animation on imageview in Pre-execute and stop it in Post-execute but app force stopped.

error: Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

here is my code:

    class RefreshAsync extends AsyncTask<Void, Void, Void> {
    Animation anim = AnimationUtils.loadAnimation(getContext(),
            R.anim.rotation);

    @Override
    protected Void doInBackground(Void... arg0) {

    }

    @Override
    protected void onPostExecute(Void result) {

        getActivity().runOnUiThread(new Runnable() {

            @Override
            public void run() {

                imageView.animate().cancel();
            }
        });

        super.onPostExecute(result);
    }

    @Override
    protected void onPreExecute() {
        getActivity().runOnUiThread(new Runnable() {

            @Override
            public void run() {

                imageView.startAnimation(anim);
            }
        });

        super.onPreExecute();
    }

}

THANKS IN ADVANCE!!