Android does not save state

Question

I recently converted my application from an activity-based application to a fragment-based application. This is a score app, and I could easily save and restore the score when it was a lesson. However, this does not work as a fragment. Here is my code:

@Override public void onSaveInstanceState(Bundle savedInstanceState){ super.onSaveInstanceState(savedInstanceState); if(t!=null&&flag==1){ savedInstanceState.putInt("time", t.getTimeLeft()); } else { savedInstanceState.putInt("time", 0); } savedInstanceState.putIntArray("score_array", points); savedInstanceState.putIntArray("position_array", spinnerPosition); savedInstanceState.putBooleanArray("checked_array", shouldBeChecked); flag = 0; Log.d("MyApp", "savingState"); } @Override public void onActivityCreated(Bundle savedInstanceState){ super.onActivityCreated(savedInstanceState); Log.d("MyApp", "onActivityCreated"); try { int timeLeft = savedInstanceState.getInt("time"); points = savedInstanceState.getIntArray("score_array").clone(); spinnerPosition = savedInstanceState.getIntArray("position_array").clone(); shouldBeChecked = savedInstanceState.getBooleanArray("checked_array").clone(); ((BaseAdapter) ((ListView)getView().findViewById(R.id.missionList)).getAdapter()).notifyDataSetChanged(); if(timeLeft!=0){ flag=1; this.getActivity().getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); t = new TimerClass(timeLeft*1000, 1000); t.setViews((TextView)getView().findViewById(R.id.minuteView), (TextView)getView().findViewById(R.id.tenSecondView), (TextView)getView().findViewById(R.id.secondView), (Button)getView().findViewById(R.id.start_button)); ((Button)getView().findViewById(R.id.start_button)).setText(R.string.stop); t.start(); } } catch (Exception e) { e.printStackTrace(); } } 

I used this exact code successfully for activity in onRestoreInstanceState , not onActivityCreated and without try / catch. The problem is that I get null pointer errors when I try to extract something from the package. I can see the save state in the log, and then onActivityCreated, but onActivityCreated does not seem to receive the stuff placed in the package by onSavedInstanceState. I just get a null pointer to every line that calls savedInstanceState.getAnything() . However, from my reading onCreate , onCreateView and onActivityCreated all use the same set. I tried translating the code to the other two without any luck.

Answer 1

In the end, I came up with a pretty hacky job. Not happy with this, since it does not solve the main problem. If anyone can help me find this, I would be happy to accept this answer.

However, I just used the onSaveInstanceState and onRestoreInstanceState activity to save and restore the fragment data.

Answer 2

For those who need a better answer:

Always check if(savedInstanceState!=null) before accessing it to avoid null pointer errors. Also, keep in mind that onSaveInstanceState () will not be able to save your data in all cases when your fragment is destroyed.

In particular, if your fragment is pushed onto the back stack and the device rotates. In this case, only onDestoryView () is called when your fragment is pushed onto the back stack, so when onSaveInstanceState () is launched while the device is spinning, it will not be able to save any data from your views because it was destroyed before.

See the following thread for a workaround. I think this is useful for anyone who develops using Fragments. Especially the DroidT answer: fooobar.com/questions/18707 / ...