DropdownButtonFormField not showing Drop down Menu Items-CodePudding

this is my code

  Padding(
                    padding: EdgeInsets.symmetric(vertical: 10.h),
                    child: DropdownButtonFormField(
                      decoration: InputDecoration(
                          labelText: "countries",
                          labelStyle: TextStyle(fontSize: 16.sp),
                          border: OutlineInputBorder(
                              borderRadius: BorderRadius.circular(10))),
                      items: const [
                        
                        DropdownMenuItem(child: Text("USA"), value: "USA"),
                        DropdownMenuItem(
                            child: Text("Canada"), value: "Canada"),
                        DropdownMenuItem(
                            child: Text("Brazil"), value: "Brazil"),
                        DropdownMenuItem(
                            child: Text("England"), value: "England"),
                      ],
                    ),
                  ),

when i click on DropDownButtonFormField the items does not appear .

CodePudding user response：

A common mistake when it is not updating is to use DropdownButtonFormField in a StatelessWidget rather than a StatefulWidget. but hard to say as you did not share that part of the code

Seems you are also missing other code in your DropdownButtonFormField

DropdownButtonFormField(
    value: myVariable,
    onChanged: (value) {
              setState(() {
                myVariable= value;
              });
            },

Let me know if this does not help.

CodePudding user response：

Anything with an interaction with user must be inside StatefulWidget. There is another ways like changenotifier using notifyListeners() inside void function. https://medium.com/@aruny3/how-to-use-changenotifier-in-flutter-440371617b8c