bobo shante

I am in jamaica and there is so local sun educational services office here. There are however Prometric testing centers. I do not have a US credit card, so how can I pay for the voucher so I can sit the exam. Does Sun accept payment by money order? If I get someone with a US credit card is there somewhere on Sun's site where I can have them pay for the exam so the voucher can be sent to me?
Please help.

I am trying to develop a simple mutlithreaded chat server. The file Server.java contains two classes one is the GUI and the other is a thread which is spawned each time a corresponding client thread is connected to it. I use a JList to show a list of online users and a Vector which stores the names as strings.
Each time a new client connects to a server thread it(the client) passes its username to the server thread which in turn has a refernce to the server frame. Each server thread adds an element to the vector which is a property of the server frame. A method of the server frame then loops through the server threads which are also in a vector and writes the updated Vector(containg the clients' names) to each respective server thread output stream.
My problem is that when the vector is received in the client thread only the last client to connect will have the full quota of names and the others will remain the same as when they were just connected.
I would really appreciate any help!

Please explain as well as you can what causes an OptionalDataException and how I may prevent or fix it

Pardon my ignorance...I'm new,
Is there a set pass mark for scjp? I have been studying java for 4 months now in JAMAICA. Also, how are the questions distributed per topic? i.e which topic will I see more questions on.
Thanks
Bobo