如何解决这个错误，模拟器启动失败。原因:在React native中找不到仿真器作为` emulators list-avds`的输出？

Question

我正在为移动应用程序创建react原生应用程序。我在构建react原生应用程序方面完全是新手。我正在使用ubuntu创建应用程序，并遵循以下链接来创建应用程序。https://facebook.github.io/react-native/docs/getting-started。有谁能解决这个问题吗？

在下面的阶段，我得到了错误：

cd AwesomeProject
npx react-native run-android

我的命令行中出现错误：

All-Series:~/Projects_App/AwesomeProject$ npx react-native run-android
info Running jetifier to migrate libraries to AndroidX. You can disable it using "--no-jetifier" flag.
Jetifier found 864 file(s) to forward-jetify. Using 4 workers...
info Starting JS server...
/bin/sh: 1: adb: not found
info Launching emulator...
error Failed to launch emulator. Reason: No emulators found as an output of `emulator -list-avds`.
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.
info Installing the app...
> Task :app:compileDebugJavaWithJavac FAILED

Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.5/userguide/command_line_interface.html#sec:command_line_warnings
13 actionable tasks: 4 executed, 9 up-to-date

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Could not find tools.jar. Please check that /usr/lib/jvm/java-8-openjdk-amd64 contains a valid JDK installation.

* 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 5s

error Failed to install the app. Make sure you have the Android development environment set up: https://facebook.github.io/react-native/docs/getting-started.html#android-development-environment. Run CLI with --verbose flag for more details.
Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:compileDebugJavaWithJavac'.
> Could not find tools.jar. Please check that /usr/lib/jvm/java-8-openjdk-amd64 contains a valid JDK installation.

* 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 5s

    at checkExecSyncError (child_process.js:621:11)
    at execFileSync (child_process.js:639:15)
    at runOnAllDevices (/home/rupeevest/Projects_App/AwesomeProject/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/runOnAllDevices.js:94:39)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)

Answer 1

转到您的react-native Project，然后转到android目录并使用此名称创建一个文件

local.properties

如果你在Windows上，打开文件并粘贴你的Android SDK路径，如下所示：

sdk.dir=C:\Users\UserName\AppData\Local\Android\sdk

我找到了正确的答案here

Answer 2

当我遇到类似问题时，我使用的一个快速修复方法是运行

react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

然后确保您的模拟器处于打开状态，并再次运行react-native run-android

Answer 3

帮助我的是在Android Studio中打开项目，并在从旁边的模拟器下拉列表中选择模拟器后按下播放按钮。

此外，如果由于某种原因，该模拟器抛出错误，请尝试使用不同的电话安装另一个模拟器。希望这对某些人有帮助！