How do I run a jar file in multiple threads?

Question

I need to run an executable JAR file in multiple threads/cores. The JAR file does not implement Runnable. I've been looking for a way to do that and haven't found one. Is it possible to make a JAR file use multiple threads/cores without having access to the source code?

Currently. if I just run the JAR file normally, it only uses a single core.

Answer 1

There is no way to magically make a program (doesn't matter if it's packaged in a Java JAR file or some other way) automatically use multiple cores. The program must have been written to make use of multiple cores - there's no other way.

Answer 2

No, you can't. You can run several java processes running the same JAR in different threads, but this might not be what you want.