flutter :无法获取特定的索引或选定内容转到另一个页面

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: Center(
        child: GestureDetector(
          onTap: () {
            Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => DetailPage()),
            );
          },
          child: Text(
            '点击跳转到详情页',
            style: TextStyle(fontSize: 20),
          ),
        ),
      ),
    );
  }
}

class DetailPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Detail'),
      ),
      body: Center(
        child: Text(
          '这是详情页',
          style: TextStyle(fontSize: 20),
        ),
      ),
    );
  }
}