Menubar in Vaadin.

public class HeaderMenu extends menubar implements View {

    public HeaderMenu() {
        Command menucommand = this::menuSelected;
        MenuItem Accounts = menubar.addItem("Accounts", null);
        MenuItem Plans = menubar.addItem("Plans", menucommand);
        MenuItem Billing = menubar.addItem("Billing", null);
        MenuItem Invoices = menubar.addItem("Invoices", null);
        MenuItem Payments = menubar.addItem("Payments", null);
        MenuItem Reports = menubar.addItem("Reports", null);
        MenuItem MyAccount = menubar.addItem("MyAccount", null);
        MenuItem SubMyAccount = MyAccount.addItem("My Account", menucommand); //binding events
        MenuItem MyRates = MyAccount.addItem("My Rates", menucommand);
        MenuItem MyInvoices = MyAccount.addItem("My Invoices", menucommand);
        MenuItem MyPayments = MyAccount.addItem("My Payments", menucommand);

        MenuItem Settings = menubar.addItem("Settings", null);
        MenuItem Help = menubar.addItem("Help", null);

        SubMyAccount.setChecked(true);
    }

    private void menuSelected(MenuItem item) {              // getting events on particular

                                                              Menu Items
        String menuItem=item.getText();
        if (item.getParent() != null)
            item.getParent().setText(item.getText());
        if (menuItem.contains("My Account")) {
            Notification.show("NO Such Wiew Exists", Notification.TYPE_WARNING_MESSAGE);
            UI.getCurrent().getNavigator().navigateTo("nop");
        }
 else if (menuItem.contains("Plans")) {
            UI.getCurrent().getNavigator().navigateTo("plan");
        }
    }
}