The MIT App Inventor 2 uses blocks to create the android application, however it does not use Java. I programmed my app in this inventor for a Google Admob student challenge, but now cannot integrate the Admob ads. This will result in my team's disqualification.
Update 12/2017
use one of the App Inventor distributions, which offer AdMob components
a list of App Inventor distributions you can find here
This is not available for MIT App Inventor, but there are personal server, which offer this feature: