How to programmatically add a submenu item to the new material design android support library

Question

I am trying to add new menu items to a submenu in the new Material Design drawer panel.

Answer 1

This is how I manipulate the sub-menu item in NavigationView

1) Create menu.xml file

2) Manipulate the menu by calling this function

        /// 

    /// 
    /// 
    /// 
    private void AddNavigationMenuItem (NavigationView navView)
    {
        navView.Menu.FindItem(Resource.Id.mnugrp_Index).SubMenu.Clear();
        navView.Menu.FindItem(Resource.Id.mnugrp_Index).SubMenu.Add("This is Index 1");
        navView.Menu.FindItem(Resource.Id.mnugrp_Index).SubMenu.Add("This is Index 2");
        navView.Menu.FindItem(Resource.Id.mnugrp_Index).SubMenu.Add("This is Index 3");
        navView.Menu.FindItem(Resource.Id.mnugrp_Index).SubMenu.Add("This is Index 4");

        navView.Menu.FindItem(Resource.Id.mnugrp_Attachment).SubMenu.Clear();
        navView.Menu.FindItem(Resource.Id.mnugrp_Attachment).SubMenu.Add("This is Attachment 1");
        navView.Menu.FindItem(Resource.Id.mnugrp_Attachment).SubMenu.Add("This is Attachment 2");
        navView.Menu.FindItem(Resource.Id.mnugrp_Attachment).SubMenu.Add("This is Attachment 3");
        navView.Menu.FindItem(Resource.Id.mnugrp_Attachment).SubMenu.Add("This is Attachment 4");
    }