Saving Data on Android

ui
: This package includes 
MainActivity.kt
. 
MainActivity
 implements the 
OnClick
 methods for each button. Because the code to read, write, encrypt and 
delete is abstracted behind 
NoteRepository
 and placed into separate classes, the 
code to handle the button click events remains the same regardless of the type of 
storage being utilized. This code is dependent on a single repository, and only the 
concrete type of the repository needs to change.
•
app
: This package includes 
Utility.kt
, which contains a utility function to produce 
Toast
 messages.
Using internal storage
The internal storage, by default, is private to your app. The system creates an 
internal storage directory for each app and names it with the app’s 
package name
. 
When you uninstall the app, files saved in the internal storage directory are deleted. 
If you need files to persist — even after the app is uninstalled — use external storage.
Are you ready to see internal storage in action?