2 main programs - how do I do that?

I have taught myself Java somewhat in isolation and somewhat to my disadvantage.

I have an application in IDEA that has two main programs for very different functions.

But each main uses many of the same classes.

I have one src tree. Maven project. When I build the artifact I hand edit the MAINFEST file and change the main class.  I know this is very bad. And I somethings forget.  At 61 I forget stuff.

What would be the right way to restruture this project into something that is better suited for the above?

thanks

eric p