title: How to save data to internal storage in android app persistently between updates?
body: <p>My android app saves user information as serialized objects in a ".ser" file that's saved to internal storage. 
  The data can be stored and retrieved and written just fine but whenever the user installs an update to the app, all the data is erased. 
  I assume the file is deleted upon installation of an update.
  My question is: how do I save data to internal storage without it getting deleted when users install updates?
  Do I have to use a different method, like SharedPreferences or SQLite?
  or can my FileOutputStream save persistently through updates?</p>