Question 128899 in Android Studio Question posted in
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Android Studio – A value of type 'bool?' can't be assigned to a variable of type 'bool'. flutter

bool isChecked = false;

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class _TasksTileState extends State<TasksTile> {   
 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;
    });
   },
  );
 }
}
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2

Answers


  1. 0

    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;

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  2. 0

    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!;
            });
          },
        );
      }
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