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Socket Problem.

Posted on 2006-11-09
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Last Modified: 2010-03-31
I have a small client server type program. On the server side I am implementing a simple
ServerSocket and I am trying to receive a buffer of bytes from the client. But I am receiving
a NullpointerException on the client side when I test this program. I cannot see what the
problem is....

PLEASE NOTE THAT IT IS MY REQUIREMENT THAT I MUST TRANSFER A byte[] FROM THE CLIENT...


Here is the Server.....
import java.io.*;
import java.net.*;

public class ComDataReceiverTest
{  
  public static void main(String[] args)
   {
     System.out.println("CounterServer started.");
 
     try {  
          ServerSocket aServerSocket = new ServerSocket(5000);
           
          for (;;)
          {
         
           Socket aSocket = aServerSocket.accept();

           InetAddress inetAdd = aSocket.getInetAddress();

           String remoteIP = inetAdd.getHostAddress();
           String remoteHostname = inetAdd.getHostName();

           int port = aSocket.getPort();

            System.out.println("Machine at IP: " + remoteIP +
                               ", with hostname: " +
                               remoteHostname + " called at port: " + port);
              //***NOTE I can see thos line is printed on the server side. So the
              //   connection is OK.
              
              
              
              //This is the area I am receiving data buffer from the Client
              DataInputStream in = new DataInputStream(aSocket.getInputStream());
        
              
              if (in== null)
               System.out.println("in Null");
              else
               System.out.println("in Not Null");
              
              //Note : I am getting "in Not Null" printed on the screen. This
              //       tells me that the DataInputStream object (in) is not null
              
              
               in.toString();
              
               byte bytes[] = null;
               int count  = in.read(bytes);
              
            aSocket.close();
           
             }
         } catch (Exception e) {System.out.println("Error: " + e);
           }  System.out.println("CounterServer stopped.");
   }}



and here is the client


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

public class TestClient
{  
  public static void main(String [] args)
  {  
 
   try
   {
     byte[] myBytes = {(byte)5,(byte)6,(byte)3,(byte)2,(byte)1,(byte)4};
     
     Socket t = new Socket("localhost", 5000);          
     DataOutputStream out = new DataOutputStream(t.getOutputStream());
     out.write(myBytes, myBytes.length, 0);
     t.close();
   }
   catch(Exception e)
   {
          System.out.println("Error: " + e);  
   }
  }
 
}


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Question by:prain
  • 2
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4 Comments
 
LVL 86

Accepted Solution

by:
CEHJ earned 500 total points
ID: 17908686
>>byte bytes[] = null;

should be

byte bytes[] = new byte[256];


or some such
0
 

Author Comment

by:prain
ID: 17908737
Ok. That error is gone. But  still get the count on the ServersSide as -1.
Why is that the bytes are not tranferred?.
0
 

Author Comment

by:prain
ID: 17908769
Ok. I found why. Thanks
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 17908779
:-)
0

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