Byte Array sending and receiving using Socket

Hi,
i am trying to semd and receive byte array using OutputStream and InputStream .. but i was getting null pointer exception..dono y it had happened..can anyone plz give me a sample code of how it works. . . .

thank u....

was the exception on the client side or the server side.
was u connecting a client socket to a server socket and reading from the server, or writing to the server.
plz help provide more details

ya...i am using client and server socket and sending using println and reading using readLine method...

I do not know what is the code:?