// Knock KNock Server


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

public class KnockKnockServer {

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

	int port = 1234;

	ServerSocket server = new ServerSocket(port);

        int State =1;

	while (true) {
	   // System.out.println("Waiting for client...");
	    Socket client = server.accept();
	   // System.out.println("Client from "+client.getInetAddress()+" connected.");
	    InputStream in = client.getInputStream();
            DataInputStream Din = new DataInputStream(in);
            OutputStream out = client.getOutputStream();
            DataOutputStream Dout = new DataOutputStream(out);
            // byte b[] = new byte[11];
           //  int num = in.read(b);
            String input = new String (Din.readUTF());

            if (State==1)
              { System.out.println ("Who's There");
                State=2;
              }
              else
                if(State==2)
                { System.out.println (input + " Who?");
                 State=3;
                 }
                else
                if(State==3)
                { System.out.println ("that was funny!");
                 State=1;
                 }

	}
    }
}

-----


//KNock KNock Client



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

public class KnockKnockClient {

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

	//the proceswing will to have to take plavce in a contiuous while loop:
        while (true)
        {
        //get a socket on the same port defined in the server; in this case 1234

          Socket server = new Socket("localhost",1234);

        //put an output stream on that socket

          OutputStream out = server.getOutputStream();

        //to let it output stings, put a DtaOutputStream on it

          DataOutputStream Dout = new DataOutputStream(out);

        //Interaction with the keyboard:

          //Make aDataInputReader to read fromstandard input

           DataInputStream termIn = new DataInputStream(System.in);

          //ask for input from user
           System.out.println("Enter next line of joke (press return to finish):");

          //read the input and call it "LineOfJoke"

           String LineOfJoke = new String (termIn.readLine());

           //Write it to the sream using the DAtaOutputStream

           Dout.writeUTF(LineOfJoke);
           }
    }
}