The argument type 'void Function()? Function(int)' can't be assigned to the parameter type 'void Function(int?)?' after null safety

Question

I want to migrate my flutter app to null safety and I have this error

The argument type 'void Function()? Function(int)' can't be assigned to the parameter type 'void Function(int?)?' in "OnTap: handleItemSelected,

_NavigationBarItem(
            index: 0,
            lable: 'Messages',
            icon: CupertinoIcons.bubble_left_bubble_right_fill,
            isSelected: (selectedIndex == 0),
            onTap: handleItemSelected,
          ),

this mis my HandleItemSelected void

 void handleItemSelected(int index) {
    setState(() {
      selectedIndex = index;
    });
    widget.onItemSelected!(index);
  }

Anyone knows why?

Answer 1

Update your code like this:

    Radio<int>(
       value: 0,
       groupValue: gvalue,
       onChanged: handleChange,
   ),



void handleChange(int? value) {
    setState(() {
      gvalue = value!;
      print(gvalue);
    });