private void do_save() {

    String name = tf_prod.getText();
    double qty = S15_update_product.get_qty(n, "");

    if (qty == 0) {
      S15_update_product.update_product(n, name);
      do_ok();

    } else {
      Prompt.call("Cannot Update, Still has available stocks");
      //            JOptionPane.showMessageDialog(null, "Cannot Update, Still has available
      // stocks");
    }
  }