Scheduled Task in Fragment returns getActivity as null

Question

I know similar type of question is asked before. Sorry to ask again.
I have a fragment in a tab FragmentActivity. Within the fragment in onActivityCreated, I have to schedule a task after every fix interval.

Timer t = new Timer();
t.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
   getActivity().runOnUiThread(new Runnable() {
            @Override
    public void run() {
        new fetchDataInBackground(ctx).execute();           //async task
    }
   });
}
}, 0, 20000);

The above code works perfectly fine, until we press the back button over the tab activity.
Once back button is pressed it throws the null pointer exception on getActivity() of above code.
I guess may be fragment have been detached from the activity therefore getActivity() is returning null. My question is how to achieve above scenario, so that the process should continue even if the back button is pressed. Any best practices?
I am returning the same instance of Fragment in getItem method from the FragmentPageAdapter.

Thanks in advance!

You are loading an image for your Fragment, does it even make sense to keep loading it, in case your Fragment doesnt exist anymore? — Daniel Bo, Sep 18 '13 at 13:57
Sorry for wrong method name. Edited the method name. I mean to say fetching any data in background. — Pawan Kumar, Sep 18 '13 at 14:00
If you want that data updated regardless whether Fragment is shown you should to it in a Service. — Yaroslav Mytkalyk, Sep 18 '13 at 14:06

score 0 · Answer 1 · answered Sep 18 '13 at 14:09

FragmentManager sets the fragment's mActivity field shortly after onAttach() and sets it to null shortly after onDetach() (see the source code), so my guess is that you are trying to execute getActivity() either too early or too late in the fragment lifecycle.

Scheduled Task in Fragment returns getActivity as null

1 Answers1

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