Checkbox(
    value: good,
    onChanged: (val) {
      setState(() {
        good = val;
      });
    }),

There is a red line under the val good = val, what is the reason?

I didn't forget to write above bool good = false;

CodePudding user response：

onChanged provide nullable bool, define as

{required void Function(bool?)? onChanged}

you can provide false on null case like

onChanged: (val) {
  setState(() {
    good = val??false;
  });
}

Find more about null-safety

CodePudding user response：

    onChanged: (val) {
      setState(() {
         good = !good; 
      });
    }

With this you can use switch good value from true to false or false to true every time you trigger this function