If your fragment already created you can just use findViewById() in your activity and just find the view you want.
So you should inform your activity that the fragment view already created through an interface for example:
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mListener = (OnViewCreatedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString() + " must implement OnArticleSelectedListener");
}
}
And then call the interface after Fragment's onCreateView.