Well, I would suggest you to try JavaSysMon:
https://github.com/jezhumble/javasysmon
Manage OS processes and get cpu and memory stats cross-platform in Java. So the good thing about it is , its cross-platform.
Currently it supports Mac OS X, Linux, Windows, and Solaris.
So that is a positive. If this can do your work, you can actually use the cross-platform feature for your application.
Maybe its not as good as Sigar, but give it a try.
