We have an existing Tomcat/Linux/Servlet/Java web server but we no longer have the developer.
We have C#/Windows code (desktop app) that does the same kind of computation/data manipulation as the web site.
I'm investigating why the two give slightly different results.

To achieve this, I would like to write a small java test exe that calls the code with specific input data and spits out the output + some debug info.

My main problem is, since I'm total newbie regarding Java: Where do I start to write that exe and call the existing classes (instead of having Tomcat somehow calls these classes) ?

I have a Ubuntu VM with Eclipse installed. The Java source code is installed and compiles.

My question mostly relates about how to setup a exe program project in Eclipse and setup the links necessery to call these exsting classes. It's not about the Java language itself (I know C#, which after all was inspired by Java)

TIA,