What tools to generate demo and beta versions of the application with minimal effort (JAVA, Android)?

Question

Java

With what tools is it possible to organize the generation of a demo or beta version from the main one, so that each time you do not edit everything manually
• Another package name
• Another name
• Another icon
• Another config
• stubs for functions, etc.),
but work with with one code, because in two projects 90+% of common java code.
Need help organizing this process.
I did not work closely with version control systems.
Thank you.

Answer 1

I use this approach and it suits me. All that you described above can.
tools.android.com/tech-docs/new-build-system/user-...