one question
in the case for example of
DataOutputStream output= new DataOutputStream(clientSocket.getOutputStream()) ;
or
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
must these objects to be created each time i need an I/O operation or just invoke a read or a write on them each time i need??? ( plus some flushing after each operaration)
You must create these objects only once, that is, after your socket has been initialized.
Both variants are possible, but it is more useful to create them only once.
If you want some buffering (to avoid sending a new TCP packet for each write command), you may want to think about putting a BufferedInputStream between the Socket and DataIn/Output:
DataOutput output = new DataOutputStream(new BufferedOutputStream(clientSocket.getOutputStream()));
DataInput input = new DataInputStream (new BufferedInputStream (clientSocket.getInputStream()));
I'm using the interfaces DataInput/DataOutput instead of the Stream classes here, since often you'll only need the methods defined there.
