What is socket programming? Create chat programs using TCP.

 Socket programming is a way of communication between two nodes (a client and a server) over a network using sockets. Sockets are endpoints of a two-way communication link between two programs running on a network. They allow data to be transferred between the client and server applications, enabling them to exchange messages, files, and other data.

Here is an example of a simple chat program using TCP sockets:

Server Code:

import java.io.*;
import java.net.*;
public class ChatServer {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8000);
        System.out.println("Server is running...");
        Socket socket = serverSocket.accept();
        System.out.println("Connected to client...");
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
        String inputLine;
        while ((inputLine = in.readLine()) != null) {
            System.out.println("Client: " + inputLine);
            out.println("Server: " + inputLine);
            if (inputLine.equals("Bye")) {
                break;
            }
        }
        in.close();
        out.close();
        socket.close();
        serverSocket.close();
    }
}

Client Code:

import java.io.*;
import java.net.*;
public class ChatClient {
    public static void main(String[] args) throws IOException {
        String serverHostname = "localhost";
        int serverPortNumber = 8000;
        Socket socket = new Socket(serverHostname, serverPortNumber);
        System.out.println("Connected to server...");
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
        String userInput;
        while ((userInput = stdIn.readLine()) != null) {
            out.println(userInput);
            System.out.println("Server: " + in.readLine());
            if (userInput.equals("Bye")) {
                break;
            }
        }
        stdIn.close();
        in.close();
        out.close();
        socket.close();
    }
}

In this example, the server listens on port 8000 for incoming connections from clients. When a client connects, the server creates input and output streams to communicate with the client. The server reads the client's messages and sends its own responses until the client sends a message containing the word "Bye".

The client connects to the server using the server's hostname and port number, and then creates input and output streams to communicate with the server. The client reads input from the user and sends it to the server, then reads the server's responses and displays them on the console. The client continues to send messages until the user enters the message "Bye".