server

package javaserverclient;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;


public class JavaServer {


    public static void main(String[] args) {
        int port = 4001;

        try(ServerSocket serverSocket = new ServerSocket(port)){

            System.out.println("server started...");

            while(true) {
                Socket socket = serverSocket.accept();
                new CommunicationThread(socket).start();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    static class CommunicationThread extends Thread{
        private Socket client;
        public CommunicationThread(Socket client){
            this.client = client;
        }

        @Override
        public void run (){
            try(Socket socket = this.client;
        ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
        ObjectInputStream in = new ObjectInputStream(socket.getInputStream());){

                int first = in.readInt();
                int second = in.readInt();
                System.out.println("server: " + first + " + " + second + " = " + (first + second));
                out.writeInt(first + second);

                out.flush();

            }
            catch (Exception e){
                e.printStackTrace();
            }
        }


    }

}