This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
That's not an error - it's a warning. The class file should have been created regardless. It tells you that the DataInputStream.readLine method should no longer be used - it is obsolete. The reason, and what to use instead, are outlined in the javadocs for that method.