【发布时间】：2020-07-20 20:21:40
【问题描述】：
第一次运行我的 react-native 应用程序时，模拟器可以运行（使用 Android Studio Galaxy Nexus）。但是，当我关闭模拟器并重试时，出现以下错误：
PS C:\Users\4chea\pexhouseV2> react-native run-android
info Running jetifier to migrate libraries to AndroidX. You can disable it using "--no-jetifier" flag.
Jetifier found 1197 file(s) to forward-jetify. Using 8 workers...
info Starting JS server...
info Launching emulator...
error Failed to launch emulator. Reason: Emulator exited before boot..
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.
info Installing the app...
> Task :app:stripDebugDebugSymbols UP-TO-DATE
Compatible side by side NDK version was not found.
> Task :app:installDebug FAILED
Skipping device 'emulator-5554' (emulator-5554): Device is OFFLINE.
Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.2/userguide/command_line_interface.html#sec:command_line_warnings
160 actionable tasks: 2 executed, 158 up-to-date
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':app:installDebug'.
> com.android.builder.testing.api.DeviceException: No online devices found.
* 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 24s
error Failed to install the app. Make sure you have the Android development environment set up: https://reactnative.dev/docs/environment-setup. Run CLI with --verbose flag for more details.
Error: Command failed: gradlew.bat app:installDebug -PreactNativeDevServerPort=8081
发生这种情况时我的模拟器处于打开状态并显示“无法连接到 Metro 服务器”
【问题讨论】：
标签： android react-native android-studio