Eclipse is where I make my living.
If your program is working, completely contained in this jar file, I'll have it in a java project, compiled and running for you.
Please specify:
Source code level (like j2se 1.1, 1.3, 1.4, etc.)
Target code level (like j2se 1.1, etc.)
Project directory layout (if different from the paths in the jar).
Satisfaction guaranteed on this one. I'll even throw in 30 minutes of Eclipse consulting/q&a if you want.