ChatClient.java

import java.awt.*;
import java.io.*;
import java.net.*;
import javax.swing.*;

// ChatClient: connects to server, shows GUI, sends/receives messages
public class ChatClient {
    private BufferedReader in;   // to read messages from server
    private PrintWriter out;     // to send messages to server
    private JFrame frame = new JFrame("Chat App"); // main window
    private JTextArea messageArea = new JTextArea(15, 40); // chat history
    private JTextField textField = new JTextField(40);     // input field
    private String role; // "Student" or "Teacher"

    public ChatClient(String role) {
        this.role = role;

        // GUI setup
        messageArea.setEditable(false);
        frame.getContentPane().add(new JScrollPane(messageArea), BorderLayout.CENTER);
        frame.getContentPane().add(textField, BorderLayout.SOUTH);
        frame.pack();

        // When user presses Enter, send message tagged with role
        textField.addActionListener(e -> {
            out.println(role + ": " + textField.getText());
            textField.setText("");
        });
    }

    private void connectToServer() throws IOException {
        // Connect to server at localhost:1234
        Socket socket = new Socket("localhost", 1234);
        in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        out = new PrintWriter(socket.getOutputStream(), true);

        // Thread to continuously listen for incoming messages
        new Thread(() -> {
            try {
                String message;
                while ((message = in.readLine()) != null) {
                    // Append received message to chat history
                    messageArea.append(message + "\n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }).start();
    }

    public static void main(String[] args) throws Exception {
        // Ask user to enter role (Student or Teacher)
        String role = JOptionPane.showInputDialog("Enter role: Student or Teacher");
        ChatClient client = new ChatClient(role);
        client.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        client.frame.setVisible(true);
        client.connectToServer();
    }
}