Java - 使用 AWT 更改 JFrame 的标题

Question

I am programming a simple multi-threaded client/server chat system. Project requirements specify: "Connection only happens when the connect button is clicked. The disconnect button should disconnect the connection.User enters Username before pressing connect button, Once the userName has been retrieved as above, it should also be added to the Titlebar of the Frame. " Basically, I have the connect button hooked-up and running.When user enter his name and presses Connect, How can I change title of Main Frame. Please help, this is my first socket programming project and I am super stumped on this one. Thanks all.

Client:

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.ArrayList;

public class ClientFrame extends Frame {

    public ClientFrame() {
        setSize(500, 500);
        setTitle("Chat Client");
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent We) {
                System.exit(0);
            }
        });
        add(new ClientPanel(), BorderLayout.CENTER);
        setVisible(true);
    }

    public static void main(String[] args) {
        new ClientFrame();
    }

} // end ClientFrame

class ClientPanel extends Panel implements ActionListener, Runnable {

    TextField tf;
    TextArea ta;
    List list;
    Button connect, disconnect;
    Socket socketToServer;
    PrintWriter pw;
    BufferedReader br;
    Thread t;
    String userName;

    public ClientPanel() {
        setLayout(new BorderLayout());
        tf = new TextField();
        ta = new TextArea();
        list = new List();
        connect = new Button("Connect");
        disconnect = new Button("Disconnect");
        Panel bPanel = new Panel();
        bPanel.add(connect);
        disconnect.setEnabled(false);
        bPanel.add(disconnect);

        tf.addActionListener(this);
        add(tf, BorderLayout.NORTH);
        add(ta, BorderLayout.CENTER);
        add(list, BorderLayout.EAST);
        add(bPanel, BorderLayout.SOUTH);

        connect.addActionListener(this);
        disconnect.addActionListener(this);

    } // end ClientPanel constructor

    public void actionPerformed(ActionEvent ae) {
        if (ae.getSource() == tf) {
            System.out.println(tf + " " + tf.getText());
            String temp = tf.getText();

            pw.println(userName + ": " + temp);
            tf.setText("");
        } else if (ae.getSource() == connect) {
            if (tf.getText() == null || tf.getText().equals("")) {
                ta.append("Must enter a name to connect\n");
            } else {
                userName = tf.getText();
                connect.setEnabled(false);
                disconnect.setEnabled(true);
                tf.setText("");
                try {
                    socketToServer = new Socket("127.0.0.1", 3000);
                    pw = new PrintWriter(new OutputStreamWriter(socketToServer.getOutputStream()), true);
                    br = new BufferedReader(new InputStreamReader(socketToServer.getInputStream()));
                } catch (UnknownHostException uhe) {
                    System.out.println(uhe.getMessage());
                } catch (IOException ioe) {
                    System.out.println(ioe.getMessage());
                }
            }

            t = new Thread(this);
            t.start();
            pw.println(userName);
            pw.println(userName + " has entered the chat.");
        } else if (ae.getSource() == disconnect) {
               connect.setEnabled(true);
                disconnect.setEnabled(false);
            try {
                tf.setText("");
                try {
                    socketToServer = new Socket("127.0.0.1", 3000);
                    pw = new PrintWriter(new OutputStreamWriter(socketToServer.getOutputStream()), true);
                    br = new BufferedReader(new InputStreamReader(socketToServer.getInputStream()));
                } catch (UnknownHostException uhe) {
                    System.out.println(uhe.getMessage());
                } catch (IOException ioe) {
                    System.out.println(ioe.getMessage());
                }

                t = new Thread(this);
                t.start();
                pw.println(userName);
                pw.println(userName + " has Disconnected the chat.");
             
                t.interrupt();
                socketToServer.close();
            } catch (IOException ioe) {
                System.out.println(ioe.getMessage());
            }
        }
    } // end actionPerformed

    public void run() {
        try {
            for (;;) {
                try {
                    String temp = br.readLine();
                    ta.append(temp + "\n");

                } catch (IOException ioe) {
                    System.out.println(ioe.getMessage());

                }
                Thread.sleep(10);
            }
        } catch (InterruptedException e) {
            pw.println("Disconnected.");
        }
    } // end run

} // end ClientPanel

Server:

import java.io.*;
import java.net.*;
import java.util.ArrayList;
import java.awt.*;

public class ThreadedServerWithPresence {

    public static void main(String[] args) {
        ArrayList<ThreadedHandlerWithPresence> handlers;
        try {
            handlers = new ArrayList<ThreadedHandlerWithPresence>();
            ServerSocket s = new ServerSocket(3000);
            for (;;) {
                Socket incoming = s.accept();
                new ThreadedHandlerWithPresence(incoming,
                        handlers).start();

            }
        } catch (Exception e) {
            System.out.println(e);
        }
    }
}

class ThreadedHandlerWithPresence extends Thread {

    Socket incoming;
    ArrayList<ThreadedHandlerWithPresence> handlers;
    PrintWriter pw;
    BufferedReader br;
    String userName;

    public ThreadedHandlerWithPresence(Socket i,
            ArrayList<ThreadedHandlerWithPresence> handlers) {
        incoming = i;
        this.handlers = handlers;
        handlers.add(this);
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserName() {
        return userName;
    }

    public void run() {
        try {
            br = new BufferedReader(new InputStreamReader(incoming.getInputStream()));

            pw = new PrintWriter(new OutputStreamWriter(incoming.getOutputStream()), true);

            String firstLine = br.readLine();
            setUserName(firstLine);

            for (;;) {

                String temp = br.readLine();
                if (temp == null) {
                    break;
                }
                System.out.println("Message read: " + temp);

                for (int i = 0; i < handlers.size(); i++) {
                    handlers.get(i).pw.println(temp);
                }
            }
        } catch (Exception e) {
            System.out.println(e);
        } finally {
            handlers.remove(this);
        }
    }
}

Answer 1

It's simple. If you have your class extended to Frame you can just simply pass the ClientFrame class to the ClientPanel like this:

add(new ClientPanel(this), BorderLayout.CENTER);

In the ClientPanle constructor you can do something like this:

JFrame clientFrame;

public ClientPanel(JFrame clientFrame) {
this.clientFrame=clientFrame;

Finally you call the desired method:

clientFrame.setTitle(userName);