How do I create and communicate with a server socket

In this Q&A, we'll go over how to create a server socket, connect to the server and send/receive messages using Socket APIs

The demo code below does it. Server and client sockets are created in separate threads, they send/receive data and exit thread after that. 

package com.javahowdoi.network;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.TimeUnit;

public class SocketDemo {

        public static class Server implements AutoCloseable{

            private ServerSocket serverSocket;

            private Socket clientSocket;

            private PrintWriter out;

            private BufferedReader in;

            public void read(int port) throws IOException {

                serverSocket = new ServerSocket(port);

                clientSocket = serverSocket.accept();

                out = new PrintWriter(clientSocket.getOutputStream(), true);

                in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

                String greeting = in.readLine();

                System.out.println(greeting);

                out.println("hello client");

            }

            public void close() throws IOException {

                in.close();

                out.close();

                clientSocket.close();

                serverSocket.close();

            }

        }

        public static class GreetClient implements AutoCloseable{

            private Socket clientSocket;

            private PrintWriter out;

            private BufferedReader in;

            public void connectAndSend(String ip, int port) throws IOException {

                clientSocket = new Socket(ip, port);

                out = new PrintWriter(clientSocket.getOutputStream(), true);

                in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

                System.out.println(sendAndReceiveMessage("hello server"));

            }

            private String sendAndReceiveMessage(String msg) throws IOException {

                out.println(msg);

                String resp = in.readLine();

                return resp;

            }

            public void close() throws IOException {

                in.close();

                out.close();

                clientSocket.close();

            }

        }

        public static void main(String[] args) throws Exception {

            ExecutorService es = Executors.newFixedThreadPool(2);

            es.submit( () ->  {

                try(Server s = new Server()){

                    s.read(6666);

                } catch(Exception e) {} }

            );

           Thread.sleep(1000);

            es.submit( () ->  {

                try(GreetClient s = new GreetClient()){

                    s.connectAndSend("localhost", 6666);

                } catch(Exception e) {} }

            );

            es.awaitTermination(2, TimeUnit.SECONDS);

            es.shutdown();

        }

}