vaadin submenu code for views

Hi i m added the File menu item creating the views, my code look like

final Class viewClass : new Class[] { Dashboard.class,
Editor.class, Ticket.class, MockupView.class }) {
navigator.addView(viewClass.getSimpleName(), viewClass);
menu.addItem(viewClass.getSimpleName(), new MenuBar.Command() {

public void menuSelected(MenuItem selectedItem) {
navigator.navigateTo(viewClass);
}
});

but how to add sub menu item inside this menu, any one can help me if you provide me exam开发者_如何学JAVAple it will be great full for me

menu.addItem returns a reference to the new menu item, which you can then use to add child items:

MenuBar.MenuItem item = menu.addItem("Parent", null);
item.addItem("Child", null);

Everything you need to know is on this Vaadin documentation page