Im Trying To Run A Run.Bat File To Play My Friends Runescape Private Server, When I Try To Connect However I Get This Error

Exception in thread "main" java.lang.NoClassDefFoundError: client
Caused by: java.lang.ClassNotFoundException: client
at$<Unknown Source>
at<Native Method>
at<Unknown Source>
at java.lang.ClassLoader.LoadClass<Unknown Source>
at sun.misc.Launder$AppClassLoader.loadClass<Unknown Source>
at java.lang.ClassLoader.loadClassInternal<Unknown Source>
Press any key to continue . . .

Any Idea's On How To fix This?