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

public class PingPongServer {
    public static void main(String[] args) throws Exception
    {
        // ServerSocket erzeugen, zu dem sich der Client verbinden kann
        ServerSocket serverSocket = null;
        serverSocket = new ServerSocket(4444);

        // Verbindung vom Client annehmen
        Socket clientSocket = null;
        clientSocket = serverSocket.accept();

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

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

        // Client begruessen
        out.println ("hello");

        // fuenfmal "pong" sagen und dann beenden
        String inputLine;
        int count = 0;
        while ((inputLine = in.readLine()) != null) {
            System.out.println("Client: " + inputLine);
            if (!inputLine.equals ("ping")) {
                System.out.println ("falsche Eingabe: " + inputLine);
                break;
            }
            if (++count <= 5) {
                out.println ("pong");
            } else {
                out.println ("end");
                break;
            }
        }

        // aufraeumen
        out.close();
        in.close();
        clientSocket.close();
        serverSocket.close();
    }
}