ChatApplet.java

/* Our chat client */
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;

class ChatClient extends Panel implements Runnable
{
    /* Display */
    private TextField textfield = new TextField();
    private TextArea textarea = new TextArea();
    private Font font = new Font(Font.SANS_SERIF, Font.PLAIN, 12);

    /* Communication */
    private Socket s;
    private PrintWriter pw;
    private BufferedReader br;

    public ChatClient(String host, int port, String nickname) {

    /* Set up display */
    setLayout(new BorderLayout());
        textarea.setFont(font);
        textfield.setFont(font);
    add(BorderLayout.SOUTH, textfield);
    add(BorderLayout.CENTER, textarea);

    /* Associate sendChat with textfield callback */
    textfield.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            sendChat(e.getActionCommand());
        }
        });

    try {
        s = new Socket(host, port);
        pw = new PrintWriter(s.getOutputStream(), true);
        br = new BufferedReader(new InputStreamReader(s.getInputStream()));

        /* Send nickname to chat server */
        pw.println(nickname);

        /* Become a thread */
        new Thread(this).start();
    } catch (IOException e) {System.out.println(e);}
    }

    /* Called whenever user hits return in the textfield */
    private void sendChat(String message) {
        pw.println(message);
        textfield.setText("");
    }

    /* Add strings from chat server to the textarea */
    public void run() {

    String message;

    try {
        while (true) {
        message = br.readLine();
        textarea.append(message + "\n");
        }
    } catch (IOException e) {System.out.println(e);}
    }
}

public class ChatApplet extends Applet
{
    public void init() {

    /* Retrieve parameters */
    int port = Integer.parseInt(getParameter("port"));
    String host = getParameter("host");
    String nickname = getParameter("nickname");

    /* Set up display */
    setLayout(new BorderLayout());
    add(BorderLayout.CENTER, new ChatClient(host, port, nickname));
    }
}