How to restore fragment state after resume w/o savedInstanceState?
android, android-fragments, android-listview
Solution
If your app is brought to front using the recent apps button, it might be that it isn't recreated, because the system didn't finish it yet. In that case only `onResume()` and following callbacks are invoked.
Conclusion: try to restore your position in `onResume()`, store the positions in `onPause()` (for recent app switches where the activity isn't recreated), extract the positions from `savedInstanceState` bundle (for orientation change where the activity is recreated).
Problem
in my app an `FragmentActivity` contains a simple `ListFragment` and I want to preserve the position to which the user has scrolled to. I did the following: ``` private int initialScrollPosition = 0; private int initialScrollYOffset = 0; @Override public void onSaveInstanceState (Bundle outState) { outState.putInt(SCROLL_POSITION, this.getListView().getFirstVisiblePosition()); View firstVisibleItemView = this.getListView().getChildAt(0); outState.putInt(SCROLL_Y_OFFSET, (firstVisibleItemView == null) ? 0 : firstVisibleItemView.getTop()); } @Override public void onActivityCreated (Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); this.restoreState(savedInstanceState); } private void restoreState(Bundle savedInstanceState) { if(savedInstanceState != null && savedInstanceState.containsKey(SCROLL_POSITION)) { this.initialScrollPosition = savedInstanceState.getInt(SCROLL_POSITION); } if(savedInstanceState != null && savedInstanceState.containsKey(SCROLL_Y_OFFSET)) { this.initialScrollYOffset = savedInstanceState.getInt(SCROLL_Y_OFFSET); } } @Override public void onStart () { super.onStart(); // some other GUI stuff this.getListView().setSelectionFromTop(this.initialScrollPosition, this.initialScrollYOffset); } ``` This solution works fine for things like display orientation changes or moving from one `Activity` of my app to the next. But if I fire up the app, scroll a bit, go back to home, and restore the App from Recents, `onActivityCreated` (or any other callbacks with the `savedInstanceState` `Bundle`) is not called and therefore the state cannot be restored. Therefore I have two questions: - What can I do to get the `savedInstanceState` after resuming without the `onXXXCreated` callbacks? - What exactly is the lifecycle doing there. I'd like to understand, why my approach fails. Thank you very much for any insight! Solution: Thx to André! I changed my `onSaveInstanceState` to this: ``` @Override public void onSaveInstanceState (Bundle outState) { this.initialScrollPosition = this.getListView().getFirstVisiblePosition(); View firstVisibleItemView = this.getListView().getChildAt(0); this.initialScrollYOffset = (firstVisibleItemView == null) ? 0 : firstVisibleItemView.getTop(); outState.putInt(SCROLL_POSITION, this.initialScrollPosition); outState.putInt(SCROLL_Y_OFFSET, this.initialScrollYOffset); } ```