Please don't post the same question to more than one forum; see our explanation here. I've deleted the other copy of this thread.
As to your question: same as you'd do it on the command line: by using a quoted or escaped blank string. Two single quotes ought to do fine.
Alternatively, there are forms over Runtime.exec() which take arrays of Strings as arguments, rather than a single String; use one of those. This will allow you to pass an empty String as an argument. Again, this is what you'd typically do when calling exec() from a C program. [ January 02, 2007: Message edited by: Ernest Friedman-Hill ]
You could quote the parameters, but it is ugly and error-prone. Use one of the multi-argument versions of Runtime.exec(), like the wise Sheriff said earlier.
Also, a version using quoting is likely to be OS-specific, whereas using the multi-argument Runtime.exec() will be OS-independent. Of course, the command you are running may be OS-specific anyway... [ January 08, 2007: Message edited by: Peter Chase ]
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.