Untitled

//Server
import java.io.*;
import java.net.*;
import java.util.*;

public class ChatServer {
    private static final int PORT = 12345;
    private static Set<PrintWriter> clientWriters = new HashSet<>();

    public static void main(String[] args) {
        System.out.println("Chat server started...");
        try (ServerSocket serverSocket = new ServerSocket(PORT)) {
            while (true) {
                new ClientHandler(serverSocket.accept()).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static class ClientHandler extends Thread {
        private Socket socket;
        private PrintWriter out;
        private BufferedReader in;
        private String clientName;

        public ClientHandler(Socket socket) {
            this.socket = socket;
        }

        public void run() {
            try {
                in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                out = new PrintWriter(socket.getOutputStream(), true);
                synchronized (clientWriters) {
                    clientWriters.add(out);
                }

                // Get client name
                clientName = in.readLine(); // Client should send its name immediately
                broadcast("User " + clientName + " has joined the chat.");

                String message;
                while ((message = in.readLine()) != null) {
                    broadcast(clientName + ": " + message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                synchronized (clientWriters) {
                    clientWriters.remove(out);
                }
                broadcast("User " + clientName + " has left the chat.");
            }
        }

        private void broadcast(String message) {
            synchronized (clientWriters) {
                for (PrintWriter writer : clientWriters) {
                    writer.println(message);
                }
            }
        }
    }
}
//Client
import java.io.*;
import java.net.*;
import java.util.Scanner;

public class ChatClient {
    private static final String SERVER_ADDRESS = "127.0.0.1";
    private static final int PORT = 12345;
    private PrintWriter out;
    private String name;

    public static void main(String[] args) {
        new ChatClient().start();
    }

    public void start() {
        try (Socket socket = new Socket(SERVER_ADDRESS, PORT)) {
            out = new PrintWriter(socket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            Scanner scanner = new Scanner(System.in);

            // Thread to listen for messages from the server
            new Thread(() -> {
                String message;
                try {
                    while ((message = in.readLine()) != null) {
                        System.out.println("\n" + message);
                        System.out.print("You: "); // Re-prompt after message
                    }
                } catch (IOException e) {
                    System.out.println("Connection closed.");
                }
            }).start();

            // Prompt for username and send it to the server
            System.out.print("Enter your name: ");
            name = scanner.nextLine();
            out.println(name);  // Send username to the server

            // Message input loop
            String message;
            while (true) {
                System.out.print("You: "); // Prompt for user input
                message = scanner.nextLine();

                if (message.equalsIgnoreCase("!Q")) {
                    out.println(name + " has left the chat.");
                    break; // Exit the loop if user types !Q
                }

                out.println(message); // Send message to server
            }

            System.out.println("Exiting the chat...");
            out.close(); // Close the PrintWriter
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}