How to solve SocketException: Failed host lookup: 'www.xyz.com' (OS Error: No address associated with hostname, errno = 7)

Adding internet permission is not only a solution.
You also have to make sure that you are online whether it is mobile or emulator

1. Make sure you are online whether it is mobile or emulator
   

2. Make sure you have given internet permission in your app's android/app/src/main/AndroidManifest.xml
   

   <uses-permission android:name="android.permission.INTERNET"/>

Try adding <uses-permission android:name="android.permission.INTERNET" /> to your AndroidManifest.xml file.

I added <uses-permission android:name="android.permission.INTERNET" /> to my manifest. I then had to restart the emulator for internet to work.

If you are using an emulator make sure that the mobile data is active

Go for AVD manager, then choose your emulator, on Actions menu click down option sign, then choose wipe data, then restart your emulator. It works for me.