bool isChecked = false;

A value of type 'bool?' can't be assigned to a variable of type 'bool'.

class _TasksTileState extends State { bool isChecked = false; @override Widget build(BuildContext context) { print('$isChecked is the value of isChecked'); return CheckboxListTile( title: Text('this is the Task 1.',style: TextStyle( decoration: isChecked? TextDecoration.lineThrough: null, ),), value: isChecked, onChanged: (newValue) { setState(() { print('$newValue is the value of newValue'); isChecked = newValue; }); }, ); } }

CodePudding user response：

problem is onChanged: (newValue), newValue is nullable, and your isChecked variable is not. you cannot assign nullable variable to non null. Either make isChecked nullable (bool? isChecked = false) or supply default value when assigning: isChecked = newValue ?? false;

CodePudding user response：

Here is correct way to use bool all you need is to add null operator

bool isChecked = false;
    
      @override
      Widget build(BuildContext context) {
        print('$isChecked is the value of isChecked');
        return CheckboxListTile(
          title: Text(
            'this is the Task 1.',
            style: TextStyle(
              decoration: isChecked ? TextDecoration.lineThrough : null,
            ),
          ),
          value: isChecked,
          onChanged: (newValue) {
            setState(() {
              print('$newValue! is the value of newValue');
              isChecked = newValue!;
            });
          },
        );
      }