Change item of Spinner menu in navigation drawer from fragment

I was try and try in a long time and finally succeed.

this is my solution:
1. in MainActivity code for set menu item:

    ....    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ....
        setDrawerItem();
        ....
    }

    public void setDrawerItem(){
    // set default item of Spinner menu
    ....
    }

    ....

2. in LoginFragment to change item of Spinner menu.
    if login is true and I was geting data to be item of Spinner menu I just call method setDrawerItem()

    ((MainActivity)getActivity()).setDrawerItem();

the problem with this simple solution has been wasting my time in 2 days..:^O:^O:p:^O:)B-)