不幸的是，flutter_app 已经停止

Question

我是颤振的初学者。我使用 vscode 进行开发。我还使用我的物理 android 设备而不是模拟器进行调试。我构建了一个简单的颤振应用程序。使用颤振运行执行。构建完成后，我的手机出现白屏，然后很快出现对话框“不幸的是，quiz_app 已停止。”，其中 quiz_app 是项目名称。我有一台 Ryzen-5 机器。这是$ flutter -v的输出：

[√] Flutter (Channel stable, v1.12.13+hotfix.8, on Microsoft Windows [Version 10.0.18363.720], locale en-IN)
    • Flutter version 1.12.13+hotfix.8 at C:\src\flutter
    • Framework revision 0b8abb4724 (5 weeks ago), 2020-02-11 11:44:36 -0800
    • Engine revision e1e6ced81d
    • Dart version 2.7.0

[√] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at C:\Users\haari\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 29.0.3
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b04)
    • All Android licenses accepted.

[!] Android Studio (version 3.6)
    • Android Studio at C:\Program Files\Android\Android Studio
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b04)

这是我做$ flutter run时的控制台日志：

Launching lib\main.dart on SM G531F in debug mode...
Running Gradle task 'assembleDebug'...
Running Gradle task 'assembleDebug'... Done                        20.0s
√ Built build\app\outputs\apk\debug\app-debug.apk.
D/FlutterActivity( 8697): Using the launch theme as normal theme.
D/FlutterActivityAndFragmentDelegate( 8697): Setting up FlutterEngine.
D/FlutterActivityAndFragmentDelegate( 8697): No preferred FlutterEngine was provided. Creating a new FlutterEngine for this FlutterFragment.
E/DartVM  ( 8697): version=2.7.0 (Fri Dec 6 16:26:51 2019 +0100) on "android_arm"
E/DartVM  ( 8697): thread=8697, isolate=vm-isolate(0xab699540)
E/DartVM  ( 8697):   pc 0x54cfcfcd fp 0xffcb8e58 libflutter.so+0x1321fcd
E/DartVM  ( 8697): -- End of DumpStackTrace

这是 main.dart 代码：-

import 'package:flutter/material.dart';

void main() => runApp(QuizApp());

class QuizApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('JIT Quiz App'),
        ),
        body: Column(
          children: <Widget>[
            Text('What is your favourite subject?'),
            RaisedButton(child: Text('DBMS'), onPressed: null),
            RaisedButton(child: Text('DAA'), onPressed: null),
            RaisedButton(child: Text('CA'), onPressed: null),
            RaisedButton(child: Text('PQT'), onPressed: null),
          ],
        ),
      ),
    );
  }
}

我尽量避免使用模拟器进行调试。

Answer 1

您应该首先返回 MaterialApp()。 MaterialApp 是您的应用程序的起点。它告诉 Flutter 你将在你的应用中使用材质组件。

Answer 2

从 Android Studio 打开您的 android 项目，然后在您的设备中运行该应用程序。 然后，您将能够在控制台中看到正确的错误消息，因为您的应用程序崩溃了。