custom classloader or setting class path on the fly

[kitguys]

hi,
Problem is
1]To load .class file from a different folder and execute it at a diffrent location. The ClassLoader class doesnt help. It gives an exception class defination not found.How can custom classloader be written?

2]How to set class path on the fly.

Please do tell us as early as possible.Its very urgent.

Detail
1)D1 is one folder it contains one class file(consider f.class).
D2 is differnt folder it contain different .class file from which we r going 2 call(create object of) the f.class file.
how to do this because we r creating .class files dynamically??????