getActivity() returns null in Fragment function

Question

I have a fragment (F1) with a public method like this

public void asd() {
    if (getActivity() == null) {
        Log.d(\"yes\",\"it is null\");
    }
}
         


        

Answer 1

This happened when you call getActivity() in another thread that finished after the fragment has been removed. The typical case is calling getActivity() (ex. for a Toast) when an HTTP request finished (in onResponse for example).

To avoid this, you can define a field name mActivity and use it instead of getActivity(). This field can be initialized in onAttach() method of Fragment as following:

@Override
public void onAttach(Context context) {
    super.onAttach(context);

    if (context instanceof Activity){
        mActivity =(Activity) context;
    }
}

In my projects, I usually define a base class for all of my Fragments with this feature:

public abstract class BaseFragment extends Fragment {

    protected FragmentActivity mActivity;

    @Override
public void onAttach(Context context) {
    super.onAttach(context);

    if (context instanceof Activity){
        mActivity =(Activity) context;
    }
}
}

Happy coding,