private void setPrefTheme(){

        // Following options to change the Theme must precede setContentView().

        SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
        String lister = sharedPref.getString("list_preference", "1");

        currentTheme = Integer.parseInt(lister);
        if(currentTheme == 2){
            isLight = false;
        } else {
            isLight = true;
        }

        if(isLight) {
            setTheme(R.style.Delta_Light);
        } else {
            setTheme(R.style.Delta_Dark);
        }

    }