6510's solution seems to work. Double-clicking it does not. I tried setting the jar extension to javaw.exe first, then when that didn't work I set it to java.exe. Neither of them worked.

If anyone's interested, here's what I came up with so far...

6510's solution seems to work. Double-clicking it does not. I tried setting the jar extension to javaw.exe first, then when that didn't work I set it to java.exe. Neither of them worked.

Just tried it and it works for me, it's definitely javaw.exe that you need.

Regarding your design, I'm not sure if I would have Gender as an alone standing class. You might have two classes, MaleSim and FemaleSim, but even that would be rather far-fetched, as the functionality of the two is likely to be near-identical. Instead, you could have an anonymous enum in the class "Sim", that has the two values MALE and FEMALE, and a variable "Gender" instead.