I tried to set the path in environmental variables but it doesn't work.
Error like as below: 'adb' is not recognized as an internal or external command, operable program or batch file.Starting the app (C:\Users\Administrator\AppData\Local\Android\Sdk/platform-tool s/adb shell am start -n com.demo/com.demo.MainActivity... Starting: Intent { cmp=com.demo/.MainActivity }
First of all you have to set environment variable of your android sdk's platform-tool
Start > Control Panel > System > Advanced System Settings > Environment Variables...
In this Environment Variables window, in the User variables section for (your-username) highlight Path and click Edit...
add this path: C:\Users\your-username\AppData\Local\Android\sdk\platform-tools;
its a default sdk path in windows OS. if you have different location than add your sdk path, than click OK until environment variable popup close.
If you already have a Command Prompt window open, close it then re-open and the adb devices command should then work.
if its still not work than add local.properties file to your project
paste your Android SDK path like below
in Windows
sdk.dir = C:/Users/USERNAME/AppData/Local/Android/sdk
in macOS
sdk.dir = /Users/USERNAME/Library/Android/sdk
in linux
sdk.dir = /home/USERNAME/Android/Sdk
Replace USERNAME with your user name
Now, Run
react-native run-android
in your terminal