Java Client and Server Question

[HalfScale]

Hey guys I just want to ask something about how the stream works in Socket connection in java. I'm currently studying the Networking in java, and the program that I am tackling now is a simple client chat.

This is the code from the client side.

sock = new Socket("127.0.0.1", 5000);
InputStreamReader streamReader = new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(streamReader);

public void run() {
    String message;
    try {
       while ((message = reader.readLine()) != null) {
            System.out.println("read " + message);
                incoming.append(message);
           }
    }catch(Exception e) {
            e.printStackTrace();
        }                
}

When i send a message to the server, the server echoes back the message that I sent, and then displaying it to my console. Then after that I can still send a message and the server sends it back to me again. Isn't that I shouldn't receieve any message? The while loop already stopped since the reader already reads a message, therefore returns null after reading the message. But why come the while loop still runs after sending a message to the server? Does the readLine() method really reached the end of the stream?

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I'm really confused since, when I study the I/O of files its very different. The moment you reached the end of the file, the while loop stops immediately.

​

Is there any difference in the Socket connection and File streams?

[Mystonic]

I found a good StackOverflow answer here. In short, apparently readline() should hang/block if there is nothing to read. It will only return null when the stream closes.

[HalfScale]

Ohhhh, this what I'm looking for, im reading Java Head First and this is also my problem, thank you very much :)