嗨，我一直在尝试在 Flutter 中使用 CheckBoxListTile

Question

          child: CheckboxListTile(
          title: Text('Eggs'),
          controlAffinity: ListTileControlAffinity.platform,
          value: _checked,
          onChanged: (bool value){
            setState(() {
              _checked = value;
            });
          },
          activeColor: Colors.white,
          checkColor: Colors.red[900],
        ),

This is the code i used. The error is showing at the _checked. It says that _checked is not defined. A new user to flutter here.

Answer 1

It says that _checked is not defined

You properly miss to define _checked .

bool _checked = false;

Answer 2

You actually need to initialize a variable in the beginning. Maybe you can do it by initializing it like:

bool _value = true //or false according to your program

or you can do this in the screen's or page's:

 class _MyStatefulWidgetState extends State<MyStatefulWidget> {
      @override
      Widget build(BuildContext context) {
        return CheckboxListTile(
          title: const Text('Animate Slowly'),
          value: timeDilation != 1.0,
          onChanged: (bool value) {
            setState(() {
              timeDilation = value ? 10.0 : 1.0;
            });
          },
        );
      }
    }

Basically, you are getting this error as you haven't initialized _checked variable.