How to return in animatedbuilder with null-safety?

Question

can anyone help me with this i am learning how to make carousel from techie blossom channel playlist Error is below in the screen shot I am struggling with null safety thing can anyone resolve this problem. İ tried with null-safety but couldn't succeed thank you 🙏🏼

Answer 1

Wrap your child inside builder with Container().

//...
builder: (BuildContext context, Widget? child) {
    return Container(child: child);
  },
//...

Here is the sample example of how to use AnimatedBuilder()

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> with 
TickerProviderStateMixin {
  late final AnimationController _controller = AnimationController(
  duration: const Duration(seconds: 10),
  vsync: this,
)..repeat();
@override
Widget build(BuildContext context) {
  return AnimatedBuilder(
    // This widget wont rebuild.
    child: Container(
      child: Text("I can not rebuild weeeee.....!!!"), color: Colors.green),
  animation: _controller,
  builder: (BuildContext context, Widget? child) {
    return Transform.rotate(
      angle: _controller.value * 2.0 * math.pi,
      // here you will pass your widget
      child: child,
     );
    },
  );
 }
}