Hi Daming,
I found that someone said sun banned nio using?
Could you be more precise, please? Who and where? It could help us replying if you gave us the links to the threads/posts you're referring to.
If you don't know how to include such links in your posts, it's explained
here (UBB codes description).
Now about your question, it really depends on your own assignment: if NIO is not explicitly disallowed in your instructions, you can use it.
Regards,
Phil.