Java-TCP socket programming

	import java.net.*;
	import java.io.*;

	public class Client1 {
	    public static void main(String[] args) throws Exception {
	        String hostAddr = "127.0.0.1"; // Loopback Address
	        int hostPort = 8000;

	        System.out.println("Client requesting for connection...");
	        Socket clientSideSocket = new Socket(hostAddr, hostPort);
	        System.out.println("Connection established.");

	        PrintWriter serverWriter = new PrintWriter(
	            clientSideSocket.getOutputStream(), true);

	        System.out.println("Key in a message for the server:");
	        serverWriter.println(new BufferedReader(
	            new InputStreamReader(System.in)).readLine());
	        System.out.println("Message sent to server.");
	    }
	}

	import java.net.*;
	import java.io.*;

	public class Server1 {
	    public static void main(String[] args) throws Exception {
	        int port = 8000;
	        ServerSocket serverSocket = new ServerSocket(port);

	        System.out.println("Server Started. Waiting for connection...");
	        Socket serverSideClientSocket = serverSocket.accept();
	        System.out.println("Client connection request received.");
	        System.out.println("Sockets bound and ready for communication.");

	        BufferedReader clientReader = new BufferedReader(new InputStreamReader(
	            serverSideClientSocket.getInputStream()));

	        System.out.println("Waiting for message from client...");
	        String messageFromClient = clientReader.readLine();
	        System.out.println("Client says: " + messageFromClient);
	    }
	}

	import java.net.*;
	import java.io.*;

	public class Client2 {
	    public static void main(String args[]) {
	        try {
	            Socket clientSideSocket = new Socket("localhost", 8000);
	            BufferedReader serverReader = new BufferedReader(
	                new InputStreamReader(clientSideSocket.getInputStream()));
	            PrintWriter serverWriter = new PrintWriter(
	                clientSideSocket.getOutputStream(), true);
	            BufferedReader keyboardReader = new BufferedReader(
	                new InputStreamReader(System.in));

	            double radius = 0;
	            while (true) {
	                System.out.print("Please enter the Radius of a Circle...");
	                radius = Double.parseDouble(keyboardReader.readLine());
	                serverWriter.println(radius);
	                if (radius != 0) {
	                    double area = Double.parseDouble(
	                        serverReader.readLine());
	                    System.out.println("Area received from the Server: " +
	                        area);
	                } else {
	                    break;
	                }
	            }
	        } catch (IOException e) {}
	    }
	}

	import java.io.*;
	import java.net.*;

	public class Server2 {
	    public static void main(String[] args) {
	        try {
	            ServerSocket serverSocket = new ServerSocket(8000);
	            Socket serverSideClientSocket = serverSocket.accept();

	            BufferedReader clientReader = new BufferedReader(
	                new InputStreamReader(
	                    serverSideClientSocket.getInputStream()));
	            PrintWriter clientWriter = new PrintWriter(
	                serverSideClientSocket.getOutputStream(), true);
	            while (true) {
	                double radius = Double.parseDouble(clientReader.readLine());
	                if (radius != 0) {
	                    System.out.println("Radius Received from Client: " +
	                        radius);
	                    double area = radius * radius * Math.PI;
	                    clientWriter.println(area);
	                } else {
	                    break;
	                }
	            }
	        } catch (IOException e) {
	            //System.out.println(e);
	        }
	    }
	}