在dart中动态初始化变量(单选按钮值)？

import 'package:flutter/material.dart';

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

class _MyWidgetState extends State<MyWidget> {
  int _selectedValue = 0;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        RadioListTile(
          title: Text('Option 1'),
          value: 1,
          groupValue: _selectedValue,
          onChanged: (value) {
            setState(() {
              _selectedValue = value;
            });
          },
        ),
        RadioListTile(
          title: Text('Option 2'),
          value: 2,
          groupValue: _selectedValue,
          onChanged: (value) {
            setState(() {
              _selectedValue = value;
            });
          },
        ),
        RadioListTile(
          title: Text('Option 3'),
          value: 3,
          groupValue: _selectedValue,
          onChanged: (value) {
            setState(() {
              _selectedValue = value;
            });
          },
        ),
      ],
    );
  }
}