See the documentation for the Runtime class for more information. However, I seem to recall running into a problem where this would not work for batch files for some reason (this was versions of Java ago; I don't remember the reason). I used the JNI and created a native method that simply wrapped C's sytem(char*) function. That worked nicely.
Piscis Babelis est parvus, flavus, et hiridicus, et est probabiliter insolitissima raritas in toto mundo.