Aktionen NUR beim ersten Starten der App ausführen?

1boolean FIRST = true;
2private SharedPreferences preferences;
3
4public void onCreate(Bundle savedInstanceState) {
5 ...
6 preferences = PreferenceManager.getDefaultSharedPreferences(this);
7 FIRST = preferences.getBoolean("firsa", true);
8 } catch (Exception e) {
9 }
10
11if(FIRST){
12 ...
13preferences = PreferenceManager.getDefaultSharedPreferences(this);
14 SharedPreferences.Editor editor = preferences.edit();
15 editor.putBoolean("firsa",false);
16 editor.commit();
17 }
18
19...