— Scott McNealy, Sun Microsystems Chairman, President and ceo

} // close SendButtonListener inner class

 public static void main(String[] args) {
new SimpleChatClientA().go();
}
 } 
// close outer class
imports for the streams (java.io), 
Socket (java.net) and the GUI 
stuff
build the GUI, nothing new 
here, and nothing related to 
networking or I/O.
This is where we make the Socket 
and the PrintWriter (it’s called 
from the go() method right before 
displaying the app GUI)
Now we actually do the writing. 
Remember, the writer is chained to 
the input stream from the Socket, so 
whenever we do a println(), it goes 
over the network to the server!
we’re using localhost so 
you can test the client 
and server on one machine
If you want to try this now, type in 
the Ready-bake chat server code 
listed at the end of this chapter . 
First, start the server in one terminal. 
Next, use another terminal to start 
this client.

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488
 
chapter 15
Version Two: send 
and receive
The Server sends a message to all 
client participants, as soon as the 
message is received by the server. 
When a client sends a message, it 
doesn’t appear in the incoming 
message display area until the 
server sends it to everyone.
outgoing message
incoming 
messages
Big Question: 
HOW do you get messages from the server?
Should be easy; when you set up the networking make an input stream as well 
(probably a BufferedReader). Then read messages using readLine().
Bigger Question: 
WHEN do you get messages from the server?
Think about that. What are the options?
Pros: Well, it’s do-able
Cons: How does the server know what you’ve seen and what you haven’t? The server 
would have to store the messages, rather than just doing a distribute-and-forget each time 
it gets one. And why 20 seconds? A delay like this affects usability, but as you reduce the 
delay, you risk hitting your server needlessly. Inefficient.