参数类型"手势检测器函数"不能分配给参数类型"小部件函数

Question

参数类型'GestureDetector Function(BuildContext，WalkthroughProvider，Widget('不能分配给参数类型'Widget Function(BuildContext，dynamic，Widget？(

class WalkthroughStepper extends StatelessWidget {
final PageController controller;
WalkthroughStepper({required this.controller}) : assert(controller != null);
@override
Widget build(BuildContext context) {
return Row(
children: List.generate(
3,
(int index) {
return Consumer(
builder: (BuildContext context, WalkthroughProvider walkthrough,
Widget child) {
return GestureDetector(
onTap: () {
controller.animateToPage(index,
duration: Duration(milliseconds: 500),
curve: Curves.ease);
},
child: Container(
color: Theme.of(context).scaffoldBackgroundColor,
padding: EdgeInsets.symmetric(vertical: 25.0),
child: Container(
height: 5.0,
width: 40.0,
decoration: BoxDecoration(
color: index <= walkthrough.currentPageValue
? Theme.of(context).primaryColor
: Colors.grey[300],
borderRadius: BorderRadius.circular(5.0),
),
margin: EdgeInsets.only(right: 5.0),
),
),
);
},
);
},
),
);
}
}

Answer 1

使回调小部件Widget child到Widget? child为空

Consumer(
builder: (BuildContext context, WalkthroughProvider walkthrough,
Widget? child) {