Programming Forums > Application Development > Java

cwl157 · Apr 18th, 2008, 2:43 PM

BinarySurfer, I have followed your suggestions but it just hangs now. I added those methods to the Server class and i assume that the ServerThread class isn't even used anymore right and that the client stays the same?

Here is the code i have after making those changes.
Server class

 java Syntax (Toggle Plain Text) 
import java.net.*;
import java.io.*;
 
//import java.net.*;
 
public class Server
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
 
    public static void main(String[] args) throws java.io.IOException
    {   
        ServerSocket s = new ServerSocket(1234);
 
          while(true)
          { 
              connection = s.accept();
              System.out.println("client connected");
              streams();
              send("Send this to client");
              //System.out.println("Listenning...");
              //(new ServerThread(s.accept())).start();
              //System.out.println("Spawned Thread.");
          } // end while
    } // end main
 
      // establish the streams
      private static void streams() throws IOException
      {
         output=new ObjectOutputStream(connection.getOutputStream());
         output.flush();
         input=new ObjectInputStream(connection.getInputStream());
      } // end streams
 
      private static void send(String or_variable)
      {
         try
         {
            output.writeObject("String" + or_variable);
            output.flush();
         } // end try
         catch(IOException ioException)
         {
         }
      } // end send
} // end Server
import java.net.*;
import java.io.*;

//import java.net.*;

public class Server
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
    
    public static void main(String[] args) throws java.io.IOException
    {   
        ServerSocket s = new ServerSocket(1234);
        
          while(true)
          { 
              connection = s.accept();
              System.out.println("client connected");
              streams();
              send("Send this to client");
              //System.out.println("Listenning...");
              //(new ServerThread(s.accept())).start();
              //System.out.println("Spawned Thread.");
          } // end while
    } // end main
    
      // establish the streams
      private static void streams() throws IOException
      {
         output=new ObjectOutputStream(connection.getOutputStream());
         output.flush();
         input=new ObjectInputStream(connection.getInputStream());
      } // end streams
      
      private static void send(String or_variable)
      {
         try
         {
            output.writeObject("String" + or_variable);
            output.flush();
         } // end try
         catch(IOException ioException)
         {
         }
      } // end send
} // end Server

Client class

 java Syntax (Toggle Plain Text) 
import java.io.*;
import java.net.*;
import java.util.*;
 
public class Client {
    public static void main(String[] args) throws IOException
    {
       Socket skt1 = new Socket("192.168.1.102", 1234);
       PrintWriter out = new PrintWriter(skt1.getOutputStream(), true);
       BufferedReader in = new BufferedReader(new InputStreamReader(
                                        skt1.getInputStream()));
       BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in));
 
       Random r = new Random();
       int[] ar = new int[10];
 
       for (int i = 0; i < 10; i++)
          ar[i] = r.nextInt(10);
 
    String line = "Send this to the other client";
    while(true)
    {
      try
      {
        // line = in.readLine();
       System.out.println("Enter something");
       out.println(keyInput.readLine());
 
         System.out.println(in.readLine());
         //out.println(line);
         for (int i = 0; i < 10; i++)
             System.out.print(ar[i] + " ");
 
         System.out.println();
 
       } // end try
      //catches bad user input and throws exception
      catch (NumberFormatException ex)
      {
    	System.out.print("Error bad data: ");
      } // end catch
    } // end while
    } // end main
} // end Client
import java.io.*;
import java.net.*;
import java.util.*;

public class Client {
    public static void main(String[] args) throws IOException
    {
       Socket skt1 = new Socket("192.168.1.102", 1234);
       PrintWriter out = new PrintWriter(skt1.getOutputStream(), true);
       BufferedReader in = new BufferedReader(new InputStreamReader(
                                        skt1.getInputStream()));
       BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in));
       
       Random r = new Random();
       int[] ar = new int[10];
       
       for (int i = 0; i < 10; i++)
          ar[i] = r.nextInt(10);
       
    String line = "Send this to the other client";
    while(true)
    {
      try
      {
        // line = in.readLine();
       System.out.println("Enter something");
       out.println(keyInput.readLine());
        
         System.out.println(in.readLine());
         //out.println(line);
         for (int i = 0; i < 10; i++)
             System.out.print(ar[i] + " ");
         
         System.out.println();
         
       } // end try
      //catches bad user input and throws exception
      catch (NumberFormatException ex)
      {
    	System.out.print("Error bad data: ");
      } // end catch
    } // end while
    } // end main
} // end Client

BinarySurfer · Apr 19th, 2008, 9:50 AM

@Freaky Chris
I've never done it that way. A better way might be to make the socket public or the send method public. Then, in the other applications, you can call the class that has the connection and use the connection or call the send class.

 java Syntax (Toggle Plain Text) 
ServerClass.send("something");
ServerClass.send("something");

I could be wrong because I have not tested it to know for myself. I have only used that accessed variable from one class to other classes, but I think the logic would work.

@cwl157
Sorry, I only got to send you the sever class, but the server looks right. The client does have to be redesigned. Not implementing what you need, here's the bare bones of the client

 java Syntax (Toggle Plain Text) 
private Socket client
private ObjectOutputStream output;
private ObjectInputStream input;
 
private void client(){
		try{
			connect();
			streams();
			processConnection();
		}
		catch (EOFException eofException){
			System.err.println("Client terminated connection");
		}
		catch (IOException ioException){
			ioException.printStackTrace();
		}
		finally{
			closeConnection();
		}
	}
	private void connect() throws IOException{
		System.out.print("Attempting Connection\n");
		client = new Socket(InetAddress.getByName(192.168.1.102), 1234);
		System.out.print("Connected to: " + client.getInetAddress().getHostName());
	}
	private void streams() throws IOException{
		output=new ObjectOutputStream(client.getOutputStream());
		output.flush();
		input=new ObjectInputStream(client.getInputStream());
		System.out.print("\nStreams Estabolished\n");
	}
	private void processConnection() throws IOException{
                String test = ""
		do{
			try{
				test = (String)input.readObject();
				System.out.print("\n" + test);
			}
			catch(ClassNotFoundException classNotFoundException){
				System.out.print("\nUnknown object recieved");
			}
		}while(!test.equals("Server Connection Lost"));
	}
	private void closeConnection(){
		try{
			output.close();
			input.close();
			client.close();
		}
		catch(IOException ioException){
			ioException.printStackTrace();
		}
	}
	private void sendData(String data){
		try{
			output.writeObject(data);
			output.flush();
		}
		catch(IOException ioException){
			System.out.print("\nError writing object");
		}
	}
private Socket client
private ObjectOutputStream output;
private ObjectInputStream input;

private void client(){
		try{
			connect();
			streams();
			processConnection();
		}
		catch (EOFException eofException){
			System.err.println("Client terminated connection");
		}
		catch (IOException ioException){
			ioException.printStackTrace();
		}
		finally{
			closeConnection();
		}
	}
	private void connect() throws IOException{
		System.out.print("Attempting Connection\n");
		client = new Socket(InetAddress.getByName(192.168.1.102), 1234);
		System.out.print("Connected to: " + client.getInetAddress().getHostName());
	}
	private void streams() throws IOException{
		output=new ObjectOutputStream(client.getOutputStream());
		output.flush();
		input=new ObjectInputStream(client.getInputStream());
		System.out.print("\nStreams Estabolished\n");
	}
	private void processConnection() throws IOException{
                String test = ""
		do{
			try{
				test = (String)input.readObject();
				System.out.print("\n" + test);
			}
			catch(ClassNotFoundException classNotFoundException){
				System.out.print("\nUnknown object recieved");
			}
		}while(!test.equals("Server Connection Lost"));
	}
	private void closeConnection(){
		try{
			output.close();
			input.close();
			client.close();
		}
		catch(IOException ioException){
			ioException.printStackTrace();
		}
	}
	private void sendData(String data){
		try{
			output.writeObject(data);
			output.flush();
		}
		catch(IOException ioException){
			System.out.print("\nError writing object");
		}
	}

That should do it.

cwl157 · Apr 19th, 2008, 10:42 AM

ok, so i changed the client and created a class that has the main method where i create a client but nothing happened. I would run the client and i never got any exceptions or messages it would just quit. I changed the sendData method to public and passed it a string but when i do that and run the client i get a nullPointerException. It occurs in the sendData method at the output.writeObject(data) line and in main at the line where i tell it to send the data. I'll post the client and server again.

Server

 java Syntax (Toggle Plain Text) 
import java.net.*;
import java.io.*;
 
//import java.net.*;
 
public class Server
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
 
    public static void main(String[] args) throws java.io.IOException
    {   
        ServerSocket s = new ServerSocket(1234);
 
          while(true)
          { 
              connection = s.accept();
              System.out.println("client connected");
              streams();
              //send("Send this to client");
              //System.out.println("Listenning...");
              //(new ServerThread(s.accept())).start();
              //System.out.println("Spawned Thread.");
          } // end while
    } // end main
 
      // establish the streams
      private static void streams() throws IOException
      {
         output=new ObjectOutputStream(connection.getOutputStream());
         output.flush();
         input=new ObjectInputStream(connection.getInputStream());
      } // end streams
 
      private static void send(String or_variable)
      {
         try
         {
            output.writeObject("String" + or_variable);
            output.flush();
         } // end try
         catch(IOException ioException)
         {
         }
      } // end send
} // end Server
import java.net.*;
import java.io.*;

//import java.net.*;

public class Server
{
    private static Socket connection;
    private static ObjectOutputStream output;
    private static ObjectInputStream input;
    
    public static void main(String[] args) throws java.io.IOException
    {   
        ServerSocket s = new ServerSocket(1234);
        
          while(true)
          { 
              connection = s.accept();
              System.out.println("client connected");
              streams();
              //send("Send this to client");
              //System.out.println("Listenning...");
              //(new ServerThread(s.accept())).start();
              //System.out.println("Spawned Thread.");
          } // end while
    } // end main
    
      // establish the streams
      private static void streams() throws IOException
      {
         output=new ObjectOutputStream(connection.getOutputStream());
         output.flush();
         input=new ObjectInputStream(connection.getInputStream());
      } // end streams
      
      private static void send(String or_variable)
      {
         try
         {
            output.writeObject("String" + or_variable);
            output.flush();
         } // end try
         catch(IOException ioException)
         {
         }
      } // end send
} // end Server

client

 java Syntax (Toggle Plain Text) 
import java.io.*;
import java.net.*;
import java.util.*;
 
public class Client
{
 
      private Socket client;
      private ObjectOutputStream output;
      private ObjectInputStream input;
 
      //Client constructor
      private void client()
      {
         try
        {
           connect();
           streams();
           processConnection();
         } // end try
         catch (EOFException eofException)
         {
            System.err.println("Client terminated connection");
         } // end catch
         catch (IOException ioException)
         {
            ioException.printStackTrace();
         } // end catch
         finally
         {
           closeConnection();
         } // end finally
      } // end client
 
      private void connect() throws IOException
      {
         System.out.print("Attempting Connection\n");
         client = new Socket(InetAddress.getByName("192.168.1.102"), 1234);
         System.out.print("Connected to: " + client.getInetAddress().getHostName());
      } // end connect
 
      private void streams() throws IOException
      {
         output=new ObjectOutputStream(client.getOutputStream());
         output.flush();
         input=new ObjectInputStream(client.getInputStream());
         System.out.print("\nStreams Estabolished\n");
      } // end streams
 
      private void processConnection() throws IOException
      {
         String test = "";
         do
         {
            try
            {
               test = (String)input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
            }while(!test.equals("Server Connection Lost")); // end do while
      } // end processConnection
 
      private void closeConnection()
      {
         try
         {
            output.close();
            input.close();
            client.close();
         } // end try
         catch(IOException ioException)
         {
            ioException.printStackTrace();
         } // end catch
      } //closeConnection
      public void sendData(String data)
      {
         try
         {
            output.writeObject(data);
            output.flush();
         } // end try
         catch(IOException ioException)
         {
            System.out.print("\nError writing object");
         } // end catch
      } // end sendData
} // end client
import java.io.*;
import java.net.*;
import java.util.*;

public class Client
{

      private Socket client;
      private ObjectOutputStream output;
      private ObjectInputStream input;
      
      //Client constructor
      private void client()
      {
         try
        {
           connect();
           streams();
           processConnection();
         } // end try
         catch (EOFException eofException)
         {
            System.err.println("Client terminated connection");
         } // end catch
         catch (IOException ioException)
         {
            ioException.printStackTrace();
         } // end catch
         finally
         {
           closeConnection();
         } // end finally
      } // end client
      
      private void connect() throws IOException
      {
         System.out.print("Attempting Connection\n");
         client = new Socket(InetAddress.getByName("192.168.1.102"), 1234);
         System.out.print("Connected to: " + client.getInetAddress().getHostName());
      } // end connect
      
      private void streams() throws IOException
      {
         output=new ObjectOutputStream(client.getOutputStream());
         output.flush();
         input=new ObjectInputStream(client.getInputStream());
         System.out.print("\nStreams Estabolished\n");
      } // end streams
      
      private void processConnection() throws IOException
      {
         String test = "";
         do
         {
            try
            {
               test = (String)input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
            }while(!test.equals("Server Connection Lost")); // end do while
      } // end processConnection

      private void closeConnection()
      {
         try
         {
            output.close();
            input.close();
            client.close();
         } // end try
         catch(IOException ioException)
         {
            ioException.printStackTrace();
         } // end catch
      } //closeConnection
      public void sendData(String data)
      {
         try
         {
            output.writeObject(data);
            output.flush();
         } // end try
         catch(IOException ioException)
         {
            System.out.print("\nError writing object");
         } // end catch
      } // end sendData
} // end client

newMain, this is the main method for the Client

 java Syntax (Toggle Plain Text) 
public class newMain 
{
   public static void main(String[] args)
   {
       Client c = new Client();
       c.sendData("here you go");
   } // end main
 
} // end newMain
public class newMain 
{
   public static void main(String[] args)
   {
       Client c = new Client();
       c.sendData("here you go");
   } // end main
 
} // end newMain

Freaky Chris · Apr 19th, 2008, 1:08 PM

BinarySurfer, i thought about making the socket public but i was thinging about the fact that if multiple peopel connect to the server then you have the issue of all the connection sockets being named the same, which of course is not going to be helpful.

However creating a class would work well, cause it would allow you to store other information about that client as well which could prove helpful. Just then remains on knowiing which class you want to check for the connection.

As i know if you use a couple of arrays then they can link niceley bassed of one thing such as a user name and from that you can then retrieive the IP from another array. But i guess you could implement something very similar with classes.

Cheers,
Chris

BinarySurfer · Apr 19th, 2008, 1:19 PM

Sorry, I think you go what I said to FreakyChris mixed in, but if you want to keep the client class separated from the game class, that's fine. In the newMain class, you have the idea down, but the problem is the Client class never attempted to established a connection with the server, which is why there is no error or output and it quits. Keeping it the way you have it, change the newMain as follows:

 java Syntax (Toggle Plain Text) 
...
 
Client c = new Client();
c.connect();
c.streams().
c.processConnection();
c.sendData("here you go");
 
...
...

Client c = new Client();
c.connect();
c.streams().
c.processConnection();
c.sendData("here you go");

...

In the newMain, Client never ran though the needed methods that establish the connection or anything. Now that the needed methods are called, it should connect and what not.
Now the server and client should connect and communicate.

cwl157 · Apr 19th, 2008, 4:59 PM

I am really confused. It does print out to all the clients a string that i enter on the server. Now how do i make it so the client can send Strings to the server and then the Server print them on all clients? I think that is the next step. That way in my game I can have the person enter their move via keyboard input and then pass it to the server which would then print it out on all clients so both clients could see all the moves. Then when there is a winner I could send that to all clients and have it displayed as well. So basically I need a method that takes a string and sends it to the server and then the server passes it to all clients which would be max 2 clients because 2 people play at once. Here is the Server class's receive method that I have been working on but does not work. I thought if this could return what is received as a String then that String could be passed into the send method and sent to all the clients. I just hangs when receive is hit.

 java Syntax (Toggle Plain Text) 
private static String receive() throws IOException
      {
         String test = "";
         try
            {
               test = (String)input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receive
private static String receive() throws IOException
      {
         String test = "";
         try
            {
               test = (String)input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receive

BinarySurfer · Apr 20th, 2008, 7:06 AM

The server and client are connected and chatting?

Quote:

Originally Posted by cwl157

Here is the Server class's receive method that I have been working on but does not work. I thought if this could return what is received as a String then that String could be passed into the send method and sent to all the clients. I just hangs when receive is hit.

 java Syntax (Toggle Plain Text) 
private static String receive() throws IOException
      {
         String test = "";
         try
            {
               test = (String)input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receive
private static String receive() throws IOException
      {
         String test = "";
         try
            {
               test = (String)input.readObject();
               System.out.print("\n" + test);
            }  // end try
            catch(ClassNotFoundException classNotFoundException)
            {
               System.out.print("\nUnknown object recieved");
            } // end catch
         return test;
      } // end receive

Well, that method is where the server accepts incoming data. Yeah, test is a lousy name now that I think of it.
For sending data, for both the client and the server, why don't you use the send method? When ever you want to send data from either, you just call the method with the info as an argument.

 java Syntax (Toggle Plain Text) 
public Client c
 
c = new Client();
c.connect();
c.streams().
c.processConnection();
... a lot of code later ...
c.sendData("5, 8");
public Client c
 
c = new Client();
c.connect();
c.streams().
c.processConnection();
... a lot of code later ...
c.sendData("5, 8");

You can put the sendData call in the same method that gets the input from the user, so the data is sent to the server and send back and to the other client.

cwl157 · Apr 20th, 2008, 11:08 AM

the receive method i posted does not work it just hangs waiting for something when its called. Also, I can just call the client's sendData method from the Server class? When i send data from the client to the server the Server never receives it. When i call sendData from the client the Server never gets it. So i thought i would need a receive method in the Server class. The send method of the Server sends the string just fine to the Client.

BinarySurfer · Apr 20th, 2008, 11:21 AM

Time's getting a little tight here now that finals are around the corner, but post your client-server classes and I know this is a stupid question, but is your firewall blocking the connection? Your Windows firewall too?

Fall Back Son · Apr 20th, 2008, 12:28 PM

Thats not a stupid question, my Client-Server program was originally being blocked by a firewall as well.

Apr 18th, 2008, 2:43 PM	#11
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 333 Rep Power: 4	Re: online game BinarySurfer, I have followed your suggestions but it just hangs now. I added those methods to the Server class and i assume that the ServerThread class isn't even used anymore right and that the client stays the same? Here is the code i have after making those changes. Server class java Syntax (Toggle Plain Text) import java.net.; import java.io.; //import java.net.; public class Server { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; public static void main(String[] args) throws java.io.IOException { ServerSocket s = new ServerSocket(1234); while(true) { connection = s.accept(); System.out.println("client connected"); streams(); send("Send this to client"); //System.out.println("Listenning..."); //(new ServerThread(s.accept())).start(); //System.out.println("Spawned Thread."); } // end while } // end main // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static void send(String or_variable) { try { output.writeObject("String" + or_variable); output.flush(); } // end try catch(IOException ioException) { } } // end send } // end Server import java.net.; import java.io.; //import java.net.; public class Server { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; public static void main(String[] args) throws java.io.IOException { ServerSocket s = new ServerSocket(1234); while(true) { connection = s.accept(); System.out.println("client connected"); streams(); send("Send this to client"); //System.out.println("Listenning..."); //(new ServerThread(s.accept())).start(); //System.out.println("Spawned Thread."); } // end while } // end main // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static void send(String or_variable) { try { output.writeObject("String" + or_variable); output.flush(); } // end try catch(IOException ioException) { } } // end send } // end Server Client class java Syntax (Toggle Plain Text) import java.io.; import java.net.; import java.util.; public class Client { public static void main(String[] args) throws IOException { Socket skt1 = new Socket("192.168.1.102", 1234); PrintWriter out = new PrintWriter(skt1.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader( skt1.getInputStream())); BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in)); Random r = new Random(); int[] ar = new int[10]; for (int i = 0; i < 10; i++) ar[i] = r.nextInt(10); String line = "Send this to the other client"; while(true) { try { // line = in.readLine(); System.out.println("Enter something"); out.println(keyInput.readLine()); System.out.println(in.readLine()); //out.println(line); for (int i = 0; i < 10; i++) System.out.print(ar[i] + " "); System.out.println(); } // end try //catches bad user input and throws exception catch (NumberFormatException ex) { System.out.print("Error bad data: "); } // end catch } // end while } // end main } // end Client import java.io.; import java.net.; import java.util.; public class Client { public static void main(String[] args) throws IOException { Socket skt1 = new Socket("192.168.1.102", 1234); PrintWriter out = new PrintWriter(skt1.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader( skt1.getInputStream())); BufferedReader keyInput = new BufferedReader(new InputStreamReader(System.in)); Random r = new Random(); int[] ar = new int[10]; for (int i = 0; i < 10; i++) ar[i] = r.nextInt(10); String line = "Send this to the other client"; while(true) { try { // line = in.readLine(); System.out.println("Enter something"); out.println(keyInput.readLine()); System.out.println(in.readLine()); //out.println(line); for (int i = 0; i < 10; i++) System.out.print(ar[i] + " "); System.out.println(); } // end try //catches bad user input and throws exception catch (NumberFormatException ex) { System.out.print("Error bad data: "); } // end catch } // end while } // end main } // end Client

Apr 19th, 2008, 9:50 AM	#12
BinarySurfer Programmer Join Date: Dec 2006 Posts: 50 Rep Power: 2	Re: online game @Freaky Chris I've never done it that way. A better way might be to make the socket public or the send method public. Then, in the other applications, you can call the class that has the connection and use the connection or call the send class. java Syntax (Toggle Plain Text) ServerClass.send("something"); ServerClass.send("something"); I could be wrong because I have not tested it to know for myself. I have only used that accessed variable from one class to other classes, but I think the logic would work. @cwl157 Sorry, I only got to send you the sever class, but the server looks right. The client does have to be redesigned. Not implementing what you need, here's the bare bones of the client java Syntax (Toggle Plain Text) private Socket client private ObjectOutputStream output; private ObjectInputStream input; private void client(){ try{ connect(); streams(); processConnection(); } catch (EOFException eofException){ System.err.println("Client terminated connection"); } catch (IOException ioException){ ioException.printStackTrace(); } finally{ closeConnection(); } } private void connect() throws IOException{ System.out.print("Attempting Connection\n"); client = new Socket(InetAddress.getByName(192.168.1.102), 1234); System.out.print("Connected to: " + client.getInetAddress().getHostName()); } private void streams() throws IOException{ output=new ObjectOutputStream(client.getOutputStream()); output.flush(); input=new ObjectInputStream(client.getInputStream()); System.out.print("\nStreams Estabolished\n"); } private void processConnection() throws IOException{ String test = "" do{ try{ test = (String)input.readObject(); System.out.print("\n" + test); } catch(ClassNotFoundException classNotFoundException){ System.out.print("\nUnknown object recieved"); } }while(!test.equals("Server Connection Lost")); } private void closeConnection(){ try{ output.close(); input.close(); client.close(); } catch(IOException ioException){ ioException.printStackTrace(); } } private void sendData(String data){ try{ output.writeObject(data); output.flush(); } catch(IOException ioException){ System.out.print("\nError writing object"); } } private Socket client private ObjectOutputStream output; private ObjectInputStream input; private void client(){ try{ connect(); streams(); processConnection(); } catch (EOFException eofException){ System.err.println("Client terminated connection"); } catch (IOException ioException){ ioException.printStackTrace(); } finally{ closeConnection(); } } private void connect() throws IOException{ System.out.print("Attempting Connection\n"); client = new Socket(InetAddress.getByName(192.168.1.102), 1234); System.out.print("Connected to: " + client.getInetAddress().getHostName()); } private void streams() throws IOException{ output=new ObjectOutputStream(client.getOutputStream()); output.flush(); input=new ObjectInputStream(client.getInputStream()); System.out.print("\nStreams Estabolished\n"); } private void processConnection() throws IOException{ String test = "" do{ try{ test = (String)input.readObject(); System.out.print("\n" + test); } catch(ClassNotFoundException classNotFoundException){ System.out.print("\nUnknown object recieved"); } }while(!test.equals("Server Connection Lost")); } private void closeConnection(){ try{ output.close(); input.close(); client.close(); } catch(IOException ioException){ ioException.printStackTrace(); } } private void sendData(String data){ try{ output.writeObject(data); output.flush(); } catch(IOException ioException){ System.out.print("\nError writing object"); } } That should do it. Last edited by BinarySurfer; Apr 19th, 2008 at 9:52 AM. Reason: Forgot to inicialize 2 objects

Apr 19th, 2008, 10:42 AM	#13
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 333 Rep Power: 4	Re: online game ok, so i changed the client and created a class that has the main method where i create a client but nothing happened. I would run the client and i never got any exceptions or messages it would just quit. I changed the sendData method to public and passed it a string but when i do that and run the client i get a nullPointerException. It occurs in the sendData method at the output.writeObject(data) line and in main at the line where i tell it to send the data. I'll post the client and server again. Server java Syntax (Toggle Plain Text) import java.net.; import java.io.; //import java.net.; public class Server { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; public static void main(String[] args) throws java.io.IOException { ServerSocket s = new ServerSocket(1234); while(true) { connection = s.accept(); System.out.println("client connected"); streams(); //send("Send this to client"); //System.out.println("Listenning..."); //(new ServerThread(s.accept())).start(); //System.out.println("Spawned Thread."); } // end while } // end main // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static void send(String or_variable) { try { output.writeObject("String" + or_variable); output.flush(); } // end try catch(IOException ioException) { } } // end send } // end Server import java.net.; import java.io.; //import java.net.; public class Server { private static Socket connection; private static ObjectOutputStream output; private static ObjectInputStream input; public static void main(String[] args) throws java.io.IOException { ServerSocket s = new ServerSocket(1234); while(true) { connection = s.accept(); System.out.println("client connected"); streams(); //send("Send this to client"); //System.out.println("Listenning..."); //(new ServerThread(s.accept())).start(); //System.out.println("Spawned Thread."); } // end while } // end main // establish the streams private static void streams() throws IOException { output=new ObjectOutputStream(connection.getOutputStream()); output.flush(); input=new ObjectInputStream(connection.getInputStream()); } // end streams private static void send(String or_variable) { try { output.writeObject("String" + or_variable); output.flush(); } // end try catch(IOException ioException) { } } // end send } // end Server client java Syntax (Toggle Plain Text) import java.io.; import java.net.; import java.util.; public class Client { private Socket client; private ObjectOutputStream output; private ObjectInputStream input; //Client constructor private void client() { try { connect(); streams(); processConnection(); } // end try catch (EOFException eofException) { System.err.println("Client terminated connection"); } // end catch catch (IOException ioException) { ioException.printStackTrace(); } // end catch finally { closeConnection(); } // end finally } // end client private void connect() throws IOException { System.out.print("Attempting Connection\n"); client = new Socket(InetAddress.getByName("192.168.1.102"), 1234); System.out.print("Connected to: " + client.getInetAddress().getHostName()); } // end connect private void streams() throws IOException { output=new ObjectOutputStream(client.getOutputStream()); output.flush(); input=new ObjectInputStream(client.getInputStream()); System.out.print("\nStreams Estabolished\n"); } // end streams private void processConnection() throws IOException { String test = ""; do { try { test = (String)input.readObject(); System.out.print("\n" + test); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch }while(!test.equals("Server Connection Lost")); // end do while } // end processConnection private void closeConnection() { try { output.close(); input.close(); client.close(); } // end try catch(IOException ioException) { ioException.printStackTrace(); } // end catch } //closeConnection public void sendData(String data) { try { output.writeObject(data); output.flush(); } // end try catch(IOException ioException) { System.out.print("\nError writing object"); } // end catch } // end sendData } // end client import java.io.; import java.net.; import java.util.; public class Client { private Socket client; private ObjectOutputStream output; private ObjectInputStream input; //Client constructor private void client() { try { connect(); streams(); processConnection(); } // end try catch (EOFException eofException) { System.err.println("Client terminated connection"); } // end catch catch (IOException ioException) { ioException.printStackTrace(); } // end catch finally { closeConnection(); } // end finally } // end client private void connect() throws IOException { System.out.print("Attempting Connection\n"); client = new Socket(InetAddress.getByName("192.168.1.102"), 1234); System.out.print("Connected to: " + client.getInetAddress().getHostName()); } // end connect private void streams() throws IOException { output=new ObjectOutputStream(client.getOutputStream()); output.flush(); input=new ObjectInputStream(client.getInputStream()); System.out.print("\nStreams Estabolished\n"); } // end streams private void processConnection() throws IOException { String test = ""; do { try { test = (String)input.readObject(); System.out.print("\n" + test); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch }while(!test.equals("Server Connection Lost")); // end do while } // end processConnection private void closeConnection() { try { output.close(); input.close(); client.close(); } // end try catch(IOException ioException) { ioException.printStackTrace(); } // end catch } //closeConnection public void sendData(String data) { try { output.writeObject(data); output.flush(); } // end try catch(IOException ioException) { System.out.print("\nError writing object"); } // end catch } // end sendData } // end client newMain, this is the main method for the Client java Syntax (Toggle Plain Text) public class newMain { public static void main(String[] args) { Client c = new Client(); c.sendData("here you go"); } // end main } // end newMain public class newMain { public static void main(String[] args) { Client c = new Client(); c.sendData("here you go"); } // end main } // end newMain

Apr 19th, 2008, 1:08 PM	#14
Freaky Chris Hobbyist Programmer Join Date: Dec 2007 Location: England Posts: 169 Rep Power: 1	Re: online game BinarySurfer, i thought about making the socket public but i was thinging about the fact that if multiple peopel connect to the server then you have the issue of all the connection sockets being named the same, which of course is not going to be helpful. However creating a class would work well, cause it would allow you to store other information about that client as well which could prove helpful. Just then remains on knowiing which class you want to check for the connection. As i know if you use a couple of arrays then they can link niceley bassed of one thing such as a user name and from that you can then retrieive the IP from another array. But i guess you could implement something very similar with classes. Cheers, Chris __________________ Who said i couldn't program `sarcasm = raw_input('Type in a sarcastic remark: ') print sarcasm`

Apr 19th, 2008, 1:19 PM	#15
BinarySurfer Programmer Join Date: Dec 2006 Posts: 50 Rep Power: 2	Re: online game Sorry, I think you go what I said to FreakyChris mixed in, but if you want to keep the client class separated from the game class, that's fine. In the newMain class, you have the idea down, but the problem is the Client class never attempted to established a connection with the server, which is why there is no error or output and it quits. Keeping it the way you have it, change the newMain as follows: java Syntax (Toggle Plain Text) ... Client c = new Client(); c.connect(); c.streams(). c.processConnection(); c.sendData("here you go"); ... ... Client c = new Client(); c.connect(); c.streams(). c.processConnection(); c.sendData("here you go"); ... In the newMain, Client never ran though the needed methods that establish the connection or anything. Now that the needed methods are called, it should connect and what not. Now the server and client should connect and communicate. Last edited by BinarySurfer; Apr 19th, 2008 at 1:20 PM. Reason: Needed more dots :P

Apr 19th, 2008, 4:59 PM	#16
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 333 Rep Power: 4	Re: online game I am really confused. It does print out to all the clients a string that i enter on the server. Now how do i make it so the client can send Strings to the server and then the Server print them on all clients? I think that is the next step. That way in my game I can have the person enter their move via keyboard input and then pass it to the server which would then print it out on all clients so both clients could see all the moves. Then when there is a winner I could send that to all clients and have it displayed as well. So basically I need a method that takes a string and sends it to the server and then the server passes it to all clients which would be max 2 clients because 2 people play at once. Here is the Server class's receive method that I have been working on but does not work. I thought if this could return what is received as a String then that String could be passed into the send method and sent to all the clients. I just hangs when receive is hit. java Syntax (Toggle Plain Text) private static String receive() throws IOException { String test = ""; try { test = (String)input.readObject(); System.out.print("\n" + test); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receive private static String receive() throws IOException { String test = ""; try { test = (String)input.readObject(); System.out.print("\n" + test); } // end try catch(ClassNotFoundException classNotFoundException) { System.out.print("\nUnknown object recieved"); } // end catch return test; } // end receive Last edited by cwl157; Apr 19th, 2008 at 5:28 PM.

Apr 20th, 2008, 11:08 AM	#18
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 333 Rep Power: 4	Re: online game the receive method i posted does not work it just hangs waiting for something when its called. Also, I can just call the client's sendData method from the Server class? When i send data from the client to the server the Server never receives it. When i call sendData from the client the Server never gets it. So i thought i would need a receive method in the Server class. The send method of the Server sends the string just fine to the Client.

Apr 20th, 2008, 11:21 AM	#19
BinarySurfer Programmer Join Date: Dec 2006 Posts: 50 Rep Power: 2	Re: online game Time's getting a little tight here now that finals are around the corner, but post your client-server classes and I know this is a stupid question, but is your firewall blocking the connection? Your Windows firewall too?

Apr 20th, 2008, 12:28 PM	#20
Fall Back Son Hobbyist Programmer Join Date: Oct 2006 Posts: 204 Rep Power: 2	Re: online game Thats not a stupid question, my Client-Server program was originally being blocked by a firewall as well.

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