Flutter: 'package get' has not been run; 'Pub get' has not been run

Dart is similar to node. It has a pubspec.yaml which is the equivalent of package.json containing your dependencies and stuff.

And you need to download these dependencies, using pub get. Or on the case of flutter, using flutter packages get.

This warning is just here to reminds you that your dependencies aren't downloaded

=> Click on Get Dependencies of the first warning

The banner 'Pub get' has not been run did not disappear even after I clicked Get dependencies and Upgrade dependencies.

Then, after I closed Android Studio and opened the same project again, the banner disappeared.