Custom Radio Button Flutter

CustomRadioButtonFlutter.dart

// The click Radio Item Example
class SizeContainer extends StatefulWidget{
  final String text;
  final bool isSelect;
  SizeContainer({this.text, this.isSelect});
  @override
  State<StatefulWidget> createState() => SizeContainerState();

}

class SizeContainerState extends State<SizeContainer>{
  
  @override
  Widget build(BuildContext context) {
    return 
      Container(
      padding: EdgeInsets.all(10),
      decoration: BoxDecoration(
        borderRadius: BorderRadius.all(Radius.circular(10)),
        color: widget.isSelect ? Colors.black : Colors.white
      ),
      child: Text(widget.text, style: TextStyle(color: widget.isSelect ? Colors.white : Colors.black, fontSize: 16)),
    );
  }

}

// Custom Radio Group
class RadioGroup extends StatefulWidget{
  @override
  State<RadioGroup> createState() => RadioGroupState();
  
}

class RadioGroupState extends State<RadioGroup>{
  
  int selectPosition = 0;
   @override
  Widget build(BuildContext context) {
    return Container(
      child:Row(
        children:<Widget>[
          GestureDetector(onTap: (){
            setState(() => selectPosition = 1);
          },
            child:SizeContainer(text: "Click 1", isSelect: selectPosition == 1)
          ),
           GestureDetector(onTap: (){
            setState(() => selectPosition = 2);
          },
            child:SizeContainer(text: "Click 2", isSelect: selectPosition == 2)
          ),
           GestureDetector(onTap: (){
            setState(() => selectPosition = 3);
          },
            child:SizeContainer(text: "Click 3", isSelect: selectPosition == 3)
          ),
           GestureDetector(onTap: (){
            setState(() => selectPosition = 4);
          },
            child:SizeContainer(text: "Click 4", isSelect: selectPosition == 4)
          ),
           GestureDetector(onTap: (){
            setState(() => selectPosition = 5);
          },
            child:SizeContainer(text: "Click 5", isSelect: selectPosition == 5)
          ),
        ]
      )
    );
    
  }

}