我在Flutter上写的代码昨天还可以，今天就黑屏了

Question

我在Flutter上写的代码昨天还可以，今天就黑屏了。我不明白。我正在学习并且没有任何错误地执行此操作非常烦人。 199 / 5,000

输入这些部分是因为需要有关 post 的更多详细信息。它仍然在等待我进一步解释这个问题。黑屏了，不知道怎么解释。

    import 'package:flutter/cupertino.dart';
    import 'package:flutter/material.dart';

    bool _valuehidra = true;
    bool _valuelight = true;
    bool _valuewebasto = true;
    bool _valueusb = true;
    bool _valuealter = true;

    void main() {
      runApp(const MaterialApp(
      ));
    }

    class MyApp extends StatefulWidget {
      const MyApp({Key? key}) : super(key: key);

      @override
      _State createState() => _State();
    }

    class _State extends State<MyApp> {
      bool isSwitched = false;

      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          home: Scaffold(
        body: Column(
        children: [
          Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
            Container(
              margin: const EdgeInsets.fromLTRB(10, 30, 0, 0),
              child: Image.asset('assets/images/logoisim.png', height: 125.0, fit: BoxFit.cover,),
            ),
            ],
          ),
          Container(

            decoration: BoxDecoration(
              color: Colors.indigoAccent,
                borderRadius: BorderRadius.circular(30.0),
            ),
            width: 350,
            height: 70,
            alignment: Alignment.bottomCenter,
            margin: const EdgeInsets.only(top: 20),
            child: Row(
              children: <Widget>[
                SizedBox(width: 200,
                  child: Container(
                    margin: const EdgeInsets.only(left: 30),
                    alignment: Alignment.centerLeft,
                    child: const Text('AYDINLATMA', style: TextStyle(color: Colors.white, fontSize: 25,fontFamily: 'YesevaOne' )),
                  ),
                ),
                Transform.scale( scale: 1.3,
                  child: Container(
                    margin: const EdgeInsets.only(left:50),
                    child: CupertinoSwitch(
                      value: _valuelight,
                      onChanged: (value) {
                        setState(() {
                          _valuelight = value;
                        });
                      },
                    ),
                  ),
                ),
              ],
            ),
          ),
          Container(
            decoration: BoxDecoration(
              color: Colors.indigo,
              borderRadius: BorderRadius.circular(30.0),
            ),
            width: 350,
            height: 70,
            alignment: Alignment.bottomCenter,
            margin: const EdgeInsets.only(top: 10),
            child: Row(
              children: <Widget>[
                SizedBox(width: 200,
                  child: Container(
                    margin: const EdgeInsets.only(left: 30),
                    alignment: Alignment.centerLeft,
                    child: const Text('WEBASTO', style: TextStyle(color: Colors.white, fontSize: 25,fontFamily: 'YesevaOne' )),
                  ),
                ),
                Transform.scale( scale: 1.3,
                  child: Container(
                    margin: const EdgeInsets.only(left:50),
                    child: CupertinoSwitch(
                      value: _valuewebasto,
                      onChanged: (value) {
                        setState(() {
                          _valuewebasto = value;
                        });
                      },
                    ),
                  ),
                ),
              ],
            ),
          ),
          Container(
            decoration: BoxDecoration(
              color: Colors.indigoAccent,
              borderRadius: BorderRadius.circular(30.0),
            ),
            width: 350,
            height: 70,
            alignment: Alignment.bottomCenter,
            margin: const EdgeInsets.only(top: 10),
            child: Row(
              children: <Widget>[
                SizedBox(width: 200,
                  child: Container(
                    margin: const EdgeInsets.only(left: 30),
                    alignment: Alignment.centerLeft,
                    child: const Text('HİDRAFOR', style: TextStyle(color: Colors.white, fontSize: 25,fontFamily: 'YesevaOne' )),
                  ),
                ),
                Transform.scale( scale: 1.3,
                  child: Container(
                    margin: const EdgeInsets.only(left:50),
                    child: CupertinoSwitch(
                      value: _valuehidra,
                      onChanged: (value) {
                        setState(() {
                          _valuehidra = value;
                        });
                      },
                    ),
                  ),
                ),
              ],
            ),
          ),
          Container(
            decoration: BoxDecoration(
              color: Colors.indigo,
              borderRadius: BorderRadius.circular(30.0),
            ),
            width: 350,
            height: 70,
            alignment: Alignment.bottomCenter,
            margin: const EdgeInsets.only(top: 10),
            child: Row(
              children: <Widget>[
                SizedBox(width: 200,
                  child: Container(
                    margin: const EdgeInsets.only(left: 30),
                    alignment: Alignment.centerLeft,
                    child: const Text('ALTERNATÖR', style: TextStyle(color: Colors.white, fontSize: 25,fontFamily: 'YesevaOne' )),
                  ),
                ),
                Transform.scale( scale: 1.3,
                  child: Container(
                    margin: const EdgeInsets.only(left:50),
                    child: CupertinoSwitch(
                      value: _valuealter,
                      onChanged: (value) {
                        setState(() {
                          _valuealter = value;
                        });
                      },
                    ),
                  ),
                ),
              ],
            ),
          ),
          Container(
            decoration: BoxDecoration(
              color: Colors.indigoAccent,
              borderRadius: BorderRadius.circular(30.0),
            ),
            width: 350,
            height: 70,
            alignment: Alignment.bottomCenter,
            margin: const EdgeInsets.only(top: 10),
            child: Row(
              children: <Widget>[
                SizedBox(width: 200,
                  child: Container(
                    margin: const EdgeInsets.only(left: 30),
                    alignment: Alignment.centerLeft,
                    child: const Text('USB (12V)', style: TextStyle(color: Colors.white, fontSize: 25,fontFamily: 'YesevaOne' )),
                  ),
                ),
                Transform.scale( scale: 1.3,
                  child: Container(
                    margin: const EdgeInsets.only(left:50),
                    child: CupertinoSwitch(
                      value: _valueusb,
                      onChanged: (value) {
                        setState(() {
                          _valueusb = value;
                        });
                      },
                    ),
                  ),
                ),
              ],
            ),
          ),
          Container(
            decoration: BoxDecoration(
              color: Colors.indigo,
              borderRadius: BorderRadius.circular(30.0),
            ),
            width: 350,
            height: 90,
            alignment: Alignment.bottomCenter,
            margin: const EdgeInsets.only(top: 10),
            child: Row(
              children: <Widget>[
                Container(
                  margin: const EdgeInsets.only(left: 30),
                  child: Image.asset('assets/images/caravan.png', height: 40.0, fit: BoxFit.cover,),
                ),
                Container(
                  margin: const EdgeInsets.only(left: 10),
                  alignment: Alignment.center,
                  child: const Text('KARAVANIM', style: TextStyle(color: Colors.white, fontSize: 31,fontFamily: 'YesevaOne' )),
                ),
                Container(
                  margin: const EdgeInsets.only(left: 10),
                  child: Image.asset('assets/images/caravan2.png', height: 40.0, fit: BoxFit.cover,),
                ),
              ],
            ),
          ),

        ],
        ),
      ),
    );
  }
}

Answer 1

您不是运行 MyApp 小部件，而是 MaterialApp

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

Answer 2

将 void main 更改为这些

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

我在Flutter上写的代码昨天还可以，今天就黑屏了

The code I wrote on Flutter was working yesterday, but today it just gives a black screen

flutter

flutter-layout