How do I save state of activities instead of always having onCreate called in Android?

Question

I would like my application to save state after it already has loaded once. For example in one of my activities I have a ListView. If the user scrolls it, and than switches activities, I wish for them to go back to the ListView activity and have the same scrolling position. I noticed that pressing the back button goes back to a saved version of the state. This is the exact kind of save I want (where it saves the state of the previous activity). Except I want to do this from anywhere in the application, not just when the back button is pressed... Please help me.

I am not looking to just save an activity with ListView. Also a map, etc. — JessThePest, Nov 24 '15 at 08:29
@ JessThePest : At `onPause()` save all your data to shared preferences and restore all data on `onResume()` ..!! — AndiGeeky, Nov 24 '15 at 08:36

score 2 · Answer 1 · edited May 23 '17 at 12:23

You have to override onSaveInstanceState(Bundle savedInstanceState) and store the values you want to save in Bundle object as name value pair.

  @Override public void onSaveInstanceState(Bundle savedInstanceState) 
    {           
    super.onSaveInstanceState(savedInstanceState); 
    savedInstanceState.putBoolean("position", 12); 
     savedInstanceState.putString("Name", "John");

           }

also you have to override onRestoreInstanceState() where you'd extract the values:

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
  super.onRestoreInstanceState(savedInstanceState);
  boolean myPosition=savedInstanceState.getBoolean("position");
  String name= savedInstanceState.getString("Name");
}

see this link for help LINK

I am trying to save a whole activity not just a few Strings and booleans :S — JessThePest, Nov 24 '15 at 08:34
@JessThePest you have to save whole activity data like this. — Amitabh Sarkar, Nov 24 '15 at 08:41

score 0 · Answer 2 · answered Nov 24 '15 at 08:35

It can be done with the saveInstanceState() and onRestoreInstanceState() methods. The first one called near onPause(), the second called before onResume(). To save the state of a view, call onSaveInstanceState() from view. For example, listview.onSaveInstnceState(); Here's a detailed article https://futurestud.io/blog/how-to-save-and-restore-the-scroll-position-and-state-of-a-android-listview

How do I save state of activities instead of always having onCreate called in Android?

2 Answers2