Flutter DropdownButtonFormField not showing selected item

Question

Using DropdownButtonFormField element to show a lists of cities. It works fine on change event and show the selected item on change event. Issue is that once I try to show selected item from set state its not working. Although state is successfully set and working.

Here is my DropdownButtonFormField code:-

              DropdownButtonFormField(
                value: _city,
                onChanged: (String newValue) {
                  setState(() {
                    _city = newValue;
                  });
                },
                // initialValue: 'Male',
                items: ['Ajman','Al Ain','Dubai','Fujairah','Ras Al Khaimah', 'Sharjah', 'Ajman','Umm Al Quwain']
                    .map((cityTitle) => DropdownMenuItem(
                    value: cityTitle, child: Text("$cityTitle")))
                    .toList(),
              )

I set _city in InitState

@override
void initState() {
  setFilters();
  super.initState();
}

setFilters(){
   setState(() {
     _city = "Dubai";
   });
}

But it's not showing selected value. How can I fix that ? Meanz when I want to set value of _city from initState its not working