Question

I was looking at the way Android handles orientation change for my application (I discovered that it restarts the mainactivity on orientation change. I’ve seen that you can override the method

protected void onSaveInstanceState(Bundle outState)

To save stuff, then have the in onStart. The problem is that I’ve my view with custom objects and a listview using a custom adapter. Everything is in a ArrayList of these objects, but I’ve noticed that you can’t put arbitrary objects in the bundle! So how do I save the state?

Answer 1

EDIT: On newer versions of Android and with the compatibility library, retained fragments are usually the best way to handle keeping expensive-to-recreate data alive across activity destruction/creation. And as Dianne pointed out, retaining nonconfiguration data was for optimizing things like thumbnail generation that are nice to save for performance reasons but not critical to your activity functioning if they need to be redone – it’s not a substitute for properly saving and restoring activity state.

But back when I first answered this in 2010:
If you want to retain your own (non view-state) data, you can actually pass an arbitrary object specifically for orientation changes using onRetainNonConfigurationInstance(). See this Android Developers blog post. Just be careful not to put any Views or other references to the pre-rotation Context/Activity in the object you pass, or you’ll prevent those objects from being garbage collected and may eventually run out of memory (this is called a context leak).