At the moment I'm a little bit confused about the lifecycle management in Android. There are at least 4 possibilities to resume retained data after an Activity comes back to the foreground:

* **Android handling:** If there is enough memory, Android stores and resumes the important data (checked radio buttons, text of EditText,-... and so on) after Activity restart, the user has the same state as before as the Activity went into background.
* **onPause, onResume:** Overriding onPause and save the important data to a database or text file and resume it when onResume is executed next time.
* **onSavedInstance(Bundle), onRestoreInstance(Bundle):** I can save the data as key-value-pair into bundles and restore them after onRestoreInstance is executed.
* **onRetainNonConfigurationInstance(), getLastNonConfigurationInstance():** I handle all my storage issues in one big object and read getLastNonConfigurationInstance() out when onCreate is executed.

Although it is confusing which approach is best, I guess it relies on development experience to know when to use which possibility. If you have some good examples for each I would be glad, but this is not my question. I wonder how to deal with all that when I have different Activities and one Activity will be killed by Android when it pauses in background: 

In my case I have a MainActivity and a MessageActivity. The MessageActivity consists of a ViewSwitcher which consists of two states. State one is a radio button choice list. State two is an EditText with two buttons (send and abort). When I monkey test each state, hit the Android home button, and restart the application, the right Activity with the right state and the old data comes into foreground, when I leave the handling to Android. So that works.  

But what happens when Android destroys the MessageActivity in background: 
If I use the Android way, the data is lost and I guess MainActivity (instead of MessageActivity->state(1 or 2)) will start next time after I relaunch the application (is that correct?). So when I'd like to keep the data of MessageActivity, I have to use one of the other three possibilities.  

How to do that neatly, when the application entry point (so the MainActivity) differs from the last active Activity. The problem is that I have to resume a special Activity with a special state of ViewSwitcher. I could start MessageActivity out of MainActivity with startActivity(Intent) in onStart() or onResume() method (because MainActivity is probably the entry point) but then I run into a lot of logical problems in Lifecycle management. Due to this fact I don't think that this is the right way to do that. 

But, what's the right and best way to do that?