Programación java

import java.io.*;
import java.net.*;
public class Provider{
 ServerSocket providerSocket;
 Socket connection = null;
 ObjectOutputStream out;
 ObjectInputStream in;
 String message;
 Provider(){}
 void run()
 {
  try{
   //1. creating a server socket
   providerSocket = new ServerSocket(2004, 10);
   //2. Wait for connection
   System.out.println("Waiting for connection");
   connection = providerSocket.accept();
   System.out.println("Connection received from " + connection.getInetAddress().getHostName());
   //3. get Input and Output streams
   out = new ObjectOutputStream(connection.getOutputStream());
   out.flush();
   in = new ObjectInputStream(connection.getInputStream());
   sendMessage("Connection successful");
   //4. The two parts communicate via the input and output streams
   do{
    try{
     message = (String)in.readObject();
     System.out.println("client>" + message);
     if (message.equals("bye"))
      sendMessage("bye");
    }
    catch(ClassNotFoundException classnot){
     System.err.println("Data received in unknown format");
    }
   }while(!message.equals("bye"));
  }
  catch(IOException ioException){
   ioException.printStackTrace();
  }
  finally{
   //4: Closing connection
   try{
    in.close();
    out.close();
    providerSocket.close();
   }
   catch(IOException ioException){
    ioException.printStackTrace();
   }
  }
 }
 void sendMessage(String msg)
 {
  try{
   out.writeObject(msg);
   out.flush();
   System.out.println("server>" + msg);
  }
  catch(IOException ioException){
   ioException.printStackTrace();
  }
 }
 public static void main(String args[])
 {
  Provider server = new Provider();
  while(true){
   server.run();
  }
 }
}
  

  import java.io.*;
import java.net.*;
public class Requester{
 Socket requestSocket;
 ObjectOutputStream out;
  ObjectInputStream in;
  String message;
 Requester(){}
 void run()
 {
  try{
   //1. creating a socket to connect to the server
   requestSocket = new Socket("localhost", 2004);
   System.out.println("Connected to localhost in port 2004");
   //2. get Input and Output streams
   out = new ObjectOutputStream(requestSocket.getOutputStream());
   out.flush();
   in = new ObjectInputStream(requestSocket.getInputStream());
   //3: Communicating with the server
   do{
    try{
     message = (String)in.readObject();
     System.out.println("server>" + message);
     sendMessage("Hi my server");
     message = "bye";
     sendMessage(message);
    }
    catch(ClassNotFoundException classNot){
     System.err.println("data received in unknown format");
    }
   }while(!message.equals("bye"));
  }
  catch(UnknownHostException unknownHost){
   System.err.println("You are trying to connect to an unknown host!");
  }
  catch(IOException ioException){
   ioException.printStackTrace();
  }
  finally{
   //4: Closing connection
   try{
    in.close();
    out.close();
    requestSocket.close();
   }
   catch(IOException ioException){
    ioException.printStackTrace();
   }
  }
 }
 void sendMessage(String msg)
 {
  try{
   out.writeObject(msg);
   out.flush();
   System.out.println("client>" + msg);
  }
  catch(IOException ioException){
   ioException.printStackTrace();
  }
 }
 public static void main(String args[])
 {
  Requester client = new Requester();
  client.run();
 }
}