Self-Extracting JAR

I have a JAR titled "SFC_Installer.jar". In in is are some classfiles and a folder called "FILES". When executed, the Jar is supposed to extract the FILES and then copy them to a user-specified directory.

I've tried it on 4 computers:

3 XP

1 Vista

It works on one of the XP's but none of the others. The problem lies on the line:

Process p = rt.exec("cmd /c jar xf SFC_Installer.jar FILES");

This is supposed to do the extracting of the FILES folder. But on the three computers where it didnt work, this line never successfully extracted the files.

Help?

Thanks in advance.

[655 byte] By [Nethera] at [2007-11-27 7:54:53]