returns the preferences saved by
Activity's class name as described in the docs :
Retrieve a SharedPreferences object for accessing preferences that are private to this activity. This simply calls the underlying getSharedPreferences(String, int) method by passing in this activity's class name as the preferences name.
While using getSharedPreferences (String name, int mode) method returns the prefs saved under the given
name. As in the docs :
Retrieve and hold the contents of the preferences file 'name', returning a SharedPreferences through which you can retrieve and modify its values.
So if the value being saved in the
SharedPreferences has to be used across the app, one should use
getSharedPreferences (String name, int mode) with a fixed name. As, using
getPreferences(int) returns/saves the preferences belonging to the
Activity calling it.