Simple Protocol Error!!

[hamad3914]

Hello Guys,

I am confused and im not being able to get through this. In this code i have to send a command to a server and get a response. But when i send Echo n i must send a number with that. When the Server replies it must reply with the number that n is. here is the questions :$

Client Request: ECHO n
Server Response: n
Meaning: Echoes n back to the client

here n is a number that starts from 0 and increments when the server requests again and again

here is the code i have till now.

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

// A server that executes a simple protocol

public class SimpleProtocolServer {
	
	public static void main(String [] args) throws IOException
	{
		final int SBAP_PORT = 8888;
		ServerSocket server = new ServerSocket(SBAP_PORT);
		System.out.println("Waiting for clients to connect...");
		
		while(true)
		{
			Socket s = server.accept();
			System.out.println("Client Connected.");
			SimpleProtocolService service = new SimpleProtocolService(s);
			Thread t = new Thread(service);
			t.start();
		}
	}
}

__________

import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class SimpleProtocolService implements Runnable {
	
	Socket s;
	int counter = 0;
    Scanner in;
    PrintWriter out;
	
	public SimpleProtocolService(Socket aSocket) 
	{
		s = aSocket;
	}
	
	public void run()
	{
		try
		{
			try
				{
					in = new Scanner(s.getInputStream());
					out = new PrintWriter(s.getOutputStream());
					
					doService();
				}
			finally
			{
				s.close();
			}
		}
			
			
		catch (IOException exception)
		{
			exception.printStackTrace();
		}
	
	
	}
	
	public void doService() throws IOException 
	{
		
		while (true)
		{
			if(!in.hasNext())
					return;
			
			String command = in.next();
			

				executeCommand(command);
		}
	}
	
	public void executeCommand(String command) {
		
		
		
		if(command.equals("HELLO"))
		{
			out.print("Greetings!");
			out.println();
			out.flush();
		}
		
		else if(command.equals("ECHO"))
		{
			counter++;
			out.print(" Echo " + counter);
			out.println();
			out.flush();
		}
		
		else if(command.equals("COUNT"))
		{
			out.print(counter);
			out.println();
			out.flush();
		}
		
		else if(command.equals("QUIT"))
		{
			out.print("goodbye");
			out.println();
			out.flush();
			return;
		}
	}
	
}

_______________

import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;


public class SimpleProtocolClient {
	
	 /**
	 This program tests the SimpleProtocolServer.
	 */
		 public static void main(String[] args) throws IOException
		 {
			 final int SBAP_PORT = 8888;
			 Socket s = new Socket("localhost", SBAP_PORT);
			 InputStream instream = s.getInputStream();
			 OutputStream outstream = s.getOutputStream();
		 
		 Scanner in = new Scanner(instream);
		 PrintWriter out = new PrintWriter(outstream);
		 
		 String command = "HELLO\n";
		 System.out.print("Sending: " + command);
		 out.print(command);
		 out.flush();
		 String response = in.nextLine();
		 System.out.println("Receiving: " + response);
		 
		 command = "ECHO n\n";
		 System.out.print("Sending: " + command);
		 out.print(command);
		 out.flush();
		 response = in.nextLine();
		 System.out.println("Receiving: " + response);
		 
		 command = "COUNT\n";
		 
		 System.out.print("Sending: " + command);
		 out.print(command);
		 out.flush();
		 response = in.nextLine();
		 System.out.println("Receiving: " + response);
		 
		 command = "QUIT\n";
		 System.out.print("Sending: " + command);
		 out.print(command);
		 out.flush();
		 response = in.nextLine();
		 System.out.println("Receiving: " + response);
		 
		 s.close();
}
}

I need help fast please guys :) THanks :D

[mrmatt1111]

I didn't run the code, but looking over the code this stands out:

if(!in.hasNext())
   return;

This will force the execution out of the loop immediately.

You probably want to change it to:

if(!in.hasNext())
   continue;

Also, you might want to put a pause in it so that you don't use up all of the CPU:

if(!in.hasNext()) {
   try { sleep(25); } catch(Exception e) {}
   continue;
}

[ra4king]

@mrmatt1111
No the return works only when the connection has closed so that is a valid statement.

@OP
So....what is your question/problem?

[hamad3914]

hmmm Thank You "mrmatt1111" :D

@ra4king ... my question is how do i make the server reply the number i type after ECHO

for eg. if i type "ECHO 10" the server must reply and print "10" :)

[ra4king]

The code looks fine, what is your problem? Is it not replying?