android app problem

[js08]

hi,

I am able to see output in ios simulator, but for android I am getting the below error. Can you tell me how to fix it

react-native run-android
info JS server already running.
info Building and installing the app on the device (cd android && ./gradlew app:installDebug)...

FAILURE: Build failed with an exception.

• What went wrong:
  A problem occurred configuring root project 'LocationTracking'.

Could not resolve all artifacts for configuration ':classpath'.
Could not resolve com.android.tools.build:gradle:3.4.0.
Required by:
project :
> Could not resolve com.android.tools.build:gradle:3.4.0.
> Could not get resource 'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle/3.4.0/gradle-3.4.0.pom'.
> Could not GET 'https://dl.google.com/dl/android/maven2/com/android/tools/build/gradle/3.4.0/gradle-3.4.0.pom'.
> sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

• 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 3s
error Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/getting-started.html
error Command failed: ./gradlew app:installDebug. Run CLI with --verbose flag for more details.