I have been searching a lot on invalidateOptionsMenu() and I know what it does. But I cannot think of any real life example where this method could be useful.

I mean, for instance, let's say we want to add a new MenuItem to our ActionBar, we can simply get the Menu from onCreateOptionsMenu(Menu menu) and use it in any button's action.

Now to my real question, is following the only way of using invalidateOptionsMenu()?

bool _OtherMenu;
protected override void OnCreate (Bundle bundle)
{
    _OtherMenu = false;
    base.OnCreate (bundle);
    SetContentView (Resource.Layout.Main);
    Button button = FindViewById<Button> (Resource.Id.myButton);
    button.Click += delegate
    {
        if(_OtherMenu)
            _OtherMenu = false;
        else
            _OtherMenu = true;

        InvalidateOptionsMenu ();
    };
}

public override bool OnCreateOptionsMenu (IMenu menu)
{
    var inflater = this.SupportMenuInflater;
    if(_OtherMenu)
        inflater.Inflate (Resource.Menu.another_menu, menu);
    else
        inflater.Inflate (Resource.Menu.main_activity_menu, menu);

    return base.OnCreateOptionsMenu (menu);
}

Click the button and a different menu appears. Click the button again and previous menu appears.

P.S. Sorry for the C# syntax.