Android codes to create an Android app

[ewpatton]

You may want to take a look at the extension template:

Extension Template Repository

Hi all, I have been experimenting on a new system for building extensions. This version no longer requires checking out the whole source tree of App Inventor to build an extension, which means that you can manage extensions in different repositories without a lot of overhead. The template repository is available on GitHub. I would appreciate feedback on this approach and how it is or isn’t working. Regards, Evan W. Patton, Ph.D. Lead Software Engineer, MIT App Inventor

You'll need to set up a few dependencies for building, such as git, the JDK, and ant.

You'll also want to review the extension authoring documentation:

App Inventor Extensions