flutter - 我正在尝试通过点击按钮来打开另一个事件，但它显示了一些错误

Question

import 'package:flutter/material.dart';

main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(primarySwatch: Colors.blue),
      home: Scaffold(
        appBar: AppBar(
          title: Text("Page 1"),
        ),
        body: Center(
          child: Column(
            children: <Widget>[
              MaterialButton(
                child: Text("Next Page"),
                onPressed: () {
                  Navigator.push(
                    context,
                    MaterialPageRoute(builder: (context) => nextPage()),
                  );
                },
                color: Colors.red,
              )
            ],
          ),
        ),
      ),
    );
  }
}

class nextPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(primarySwatch: Colors.green),
      home: Scaffold(
        appBar: AppBar(
          title: Text("Page 2"),
        ),
        body: Center(
          child: Column(
            children: <Widget>[
              MaterialButton(
                child: Text("Go Back!"),
                onPressed: () {
                  Navigator.pop(context);
                },
                color: Colors.red,
              )
            ],
          ),
        ),
      ),
    );
  }
}

这是我用来导航到新页面的代码，但是即使编译器未引发任何错误，我也遇到了问题

这是我收到的错误消息

引发了另一个异常:在不包含导航器的上下文中请求了导航器操作。

单击按钮时出现此错误

Answer 1

您需要home : Builder( builder: (context) =>和Second Page删除MaterialApp

MaterialApp(
      home: Builder(
        builder: (context) => Scaffold(
          appBar: AppBar(
            title: Text("Page 1"),
          ),
          body: Center(
            child: Column(
              children: <Widget>[
                MaterialButton(
                  child: Text("Next Page"),
                  onPressed: () {
                    Navigator.push(
                      context,
                      MaterialPageRoute(builder: (context) => nextPage()),
                    );
                  },
                  color: Colors.red,
                )
              ],
            ),
          ),
        ),
      ),

完整的代码

    import 'package:flutter/material.dart';

main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Builder(
        builder: (context) => Scaffold(
          appBar: AppBar(
            title: Text("Page 1"),
          ),
          body: Center(
            child: Column(
              children: <Widget>[
                MaterialButton(
                  child: Text("Next Page"),
                  onPressed: () {
                    Navigator.push(
                      context,
                      MaterialPageRoute(builder: (context) => nextPage()),
                    );
                  },
                  color: Colors.red,
                )
              ],
            ),
          ),
        ),
      ),
    );
  }
}

class nextPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Page 2"),
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            MaterialButton(
              child: Text("Go Back!"),
              onPressed: () {
                Navigator.pop(context);
              },
              color: Colors.red,
            )
          ],
        ),
      ),
    );
  }
}