ChatClient.java

import java.io.*;
import java.net.*;
import java.util.Scanner;

public    class ChatServer {
    public static void main(String[] args) {
        try (ServerSocket serverSocket = new ServerSocket(12345)) {
            System.out.println("Server started. Waiting for clients...");
            Socket socket = serverSocket.accept();
            System.out.println("Client connected.");

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            Scanner scanner = new Scanner(System.in);
            
            Thread receiveThread = new Thread(() -> {
                try {
                    String message;
                    while ((message = in.readLine()) != null) {
                        System.out.println("Client: " + message);
                    }
                } catch (IOException e) {
                    System.out.println("Connection closed.");
                }
            });
            receiveThread.start();

            while (true) {
                String message = scanner.nextLine();
                out.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public  class ChatClient {
    public static void main(String[] args) {
        try (Socket socket = new Socket("localhost", 12345)) {
            System.out.println("Connected to server.");

            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            Scanner scanner = new Scanner(System.in);
            
            Thread receiveThread = new Thread(() -> {
                try {
                    String message;
                    while ((message = in.readLine()) != null) {
                        System.out.println("Server: " + message);
                    }
                } catch (IOException e) {
                    System.out.println("Connection closed.");
                }
            });
            receiveThread.start();

            while (true) {
                String message = scanner.nextLine();
                out.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}