Application crushes and throw NullPointerException while Orientation is changing

Question

I am using Fragment and put AsyncTask inside it to do some network oriented task. Everything works fine. When I change the orientation from protrait to landscape, it also wors fine. But when I changed the orientation again to portrait, it crashes. This is my trying code.

public class ProblemStatistics extends SherlockProgressFragment {
    View mContentView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        mContentView = inflater.inflate(R.layout.submission_statistics,
                container, false);
        return super.onCreateView(inflater, container, savedInstanceState);
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        setContentShown(false);
        setContentView(mContentView);
        Bundle bundle = this.getArguments();
        int problemNo = 100;
        if (bundle != null) {
            problemNo = bundle.getInt("problem_no", problemNo);
        }
        new GetProblemStatisticTask().execute(CommonUtils.SPECIFIC_PROBLEM_URL + problemNo);
    }

    @Override
    public void onStop() {
        ((MainActivity) getSherlockActivity()).setProblemStatistics(false);
        super.onStop();
    }

    protected class GetProblemStatisticTask extends
            AsyncTask<String, Void, InputStreamReader> {

        @Override
        protected InputStreamReader doInBackground(String... params) {
            return new JSONDownloader().getJSONStringFromUrl(params[0]);
        }

        @Override
        protected void onPostExecute(InputStreamReader isr) {
            super.onPostExecute(isr);
            // other stuff and parsing related code
            layout.addView(gView);
            setContentShown(true);
        }
    }

}

And this is my error log:

08-16 00:07:18.025: E/AndroidRuntime(542): java.lang.NullPointerException
08-16 00:07:18.025: E/AndroidRuntime(542):  at me.kaidul.uhunt.LatestSubmissions$GetSubmissionsListTask.onPostExecute(LatestSubmissions.java:84)
08-16 00:07:18.025: E/AndroidRuntime(542):  at me.kaidul.uhunt.LatestSubmissions$GetSubmissionsListTask.onPostExecute(LatestSubmissions.java:1)
08-16 00:07:18.025: E/AndroidRuntime(542):  at android.os.AsyncTask.finish(AsyncTask.java:417)
08-16 00:07:18.025: E/AndroidRuntime(542):  at android.os.AsyncTask.access$300(AsyncTask.java:127)
08-16 00:07:18.025: E/AndroidRuntime(542):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
08-16 00:07:18.025: E/AndroidRuntime(542):  at android.os.Handler.dispatchMessage(Handler.java:99)
08-16 00:07:18.025: E/AndroidRuntime(542):  at android.os.Looper.loop(Looper.java:123)
08-16 00:07:18.025: E/AndroidRuntime(542):  at android.app.ActivityThread.main(ActivityThread.java:4627)
08-16 00:07:18.025: E/AndroidRuntime(542):  at java.lang.reflect.Method.invokeNative(Native Method)
08-16 00:07:18.025: E/AndroidRuntime(542):  at java.lang.reflect.Method.invoke(Method.java:521)
08-16 00:07:18.025: E/AndroidRuntime(542):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-16 00:07:18.025: E/AndroidRuntime(542):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-16 00:07:18.025: E/AndroidRuntime(542):  at dalvik.system.NativeStart.main(Native Method)

http://www.androiddesignpatterns.com/2013/04/retaining-objects-across-config-changes.html check this might help — Raghunandan, Aug 15 '13 at 17:34
check this http://stackoverflow.com/questions/4584015/handle-screen-orientation-changes-when-there-are-asynctasks-running — Rahul, Aug 15 '13 at 17:36

Goca · Accepted Answer · 2014-10-30T20:59:49.430

4

When orientation of the phone changes, your activity is destroyed and created again.

You can use this in AndroidManifest.xml.

activity
   your activity...
   android:configChanges="orientation|keyboardHidden|screenSize">
 activity

Edited:

As complementary for this answer:

The documentations says:"A fragment must always be embedded in an activity and the fragment's lifecycle is directly affected by the host activity's lifecycle. For example, when the activity is paused, so are all fragments in it, and when the activity is destroyed, so are all fragments."

Here is the link http://developer.android.com/guide/components/fragments.html

You can't recreate your activity only for some fragments, you should rethink your approach.

edited Oct 30 '14 at 20:59

answered Aug 15 '13 at 17:36

Goca

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I don't want to let my `activity` to be recreated. :( – Kaidul Aug 15 '13 at 17:40
Well if you add this code your activity will not be recreated, right now your activity is being created every time you change the orientation. – Goca Aug 15 '13 at 17:45
problem is, for some `Fragment` I need to `recreate` the activity, how can I specify this? - acitivty will recreated from some fragment and sometimes not? – Kaidul Aug 15 '13 at 18:19

Application crushes and throw NullPointerException while Orientation is changing

1 Answers1