Including a SettingsActivity in your Android Studio Project

Basic steps

1 - Use existing Android Studio project or create a new project. If new, start with a Basic Activity so that the Settings pulldown is available under the Options menu.

2 - It might be good to test deploy to make sure everyting is working ok.

3 - Create a new SettingsActivity. File -> New -> Activity -> SettingsActivity

4 - Link the new Activity to the Options menu. Navigate to app -> java -> <<your package>> -> MainActivity.java and add the following to onOptionsItemSelected():

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // ...
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            Intent intent = new Intent(getApplicationContext(), SettingsActivity.class); //*** ADD THESE LINES !! ***
            startActivity(intent);                                                       //***  ----------------  ***
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    
5 - Confirm that the Settings Activity is accessible from the Options menu pulldown.
    
6 - In order to access the new preferences, add this onResume to your MainActivity.java:
    
    @Override
    protected void onResume() {
       super.onResume();
       SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
       for (Map.Entry<String, ?> entry : prefs.getAll().entrySet()) 
           Log.d("SETTINGS", entry.getKey() + ": " + entry.getValue().toString());
       Log.d("SETTINGS", "switch = " + prefs.getBoolean("example_switch", false));

    }
        
7 - Just as in the for loop in step 6, you can access all of the preferences and use them in your MainActivity!

8 - To access a single preference, follow the example in the second log statement. 
    
9 - The default SettingsActivity.java may be a bit more complex than what you need. You can pare down the layouts and streamline the templated solution for your app's needs.