Preferences

https://developer.android.com/training/basics/data-storage/shared-preferences.html

Common

Common SharedPreferences sharedPref = <Activity>.getPreferences(Context.MODE_PRIVATE);

Write

Write SharedPreferences.Editor <editor> = <sharedPref>.edit();

Write editor.putBoolean(getString(R.string.<key>), <value>);

Editor.apply();.

Commit : immediate, blocking.

Read

Boolean isAlreadyLaunched;.

IsAlreadyLaunched = sharedPref.getBoolean(getString(R.string.launched), false);.