Flutter 应用程序在最新更新后无法运行答案

【问题标题】：Flutter App Failed To Run after latest UpdateFlutter 应用程序在最新更新后无法运行
【发布时间】：2020-10-24 14:18:52
【问题描述】：

环境详情 Windows + VS 代码 Flutter 1.17.5 • 通道稳定 • https://github.com/flutter/flutter.git 框架 • 修订版 8af6b2f038（3 天前） • 2020-06-30 12:53:55 -0700 引擎 • 修订版 ee76268252 工具• Dart 2.8.4

来自调试控制台的错误

E:\apps\flutterCode\android\app\src\main\java\com\example\testApp\MainActivity.java:3: error: package android.support.annotation does not exist
import android.support.annotation.NonNull;
                                 ^
E:\apps\flutterCode\android\app\src\main\java\com\example\TestApp\MainActivity.java:10: error: cannot find symbol
  public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
                                      ^
  symbol:   class NonNull
  location: class MainActivity
2 errors

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 10s
Exception: Gradle task assembleDebug failed with exit code 1

【问题讨论】：

我找到了一个解决方法，新建一个flutter项目，复制android文件夹然后替换旧项目中的android文件夹。

标签： android flutter dart

【解决方案1】：

尝试将Android/build.gradle 中的最低 SDK 版本从 16 更改为 21。如果仍然无法正常工作，请尝试如下更改build type 函数。

buildTypes {
        release {
            minifyEnabled true
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }

【讨论】：