[Android][Fixed] java.net.UnknownHostException

The reason why cause this error is because your app don't have the permission to access internet.
you can add these 2 lines to AndroidManifest.xml to give the app the permission and stop the problem.

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

This image shown where you add the statement :

In fact: add this line only is also okay.
<uses-permission android:name="android.permission.INTERNET" />