NullPointerException in out.println(message);

Question

Am trying to send a String to a server but getting a NullPointerException on line 46 thats this line:
out.println(message);
the code :
import java.sql.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.applet.Applet;
import java.io.*;
import java.net.*;
import java.util.*;
import java.applet.AudioClip;
import javax.swing.text.html.*;
import java.net.URL;
import java.io.IOException;
public class chatClient extends JApplet implements Runnable
private String hostname, message;
protected BufferedReader in;
protected PrintWriter out;
protected TextArea output;
protected TextField input;
protected Button b;
protected Thread listener;
// Constructor looks after GUI
public chatClient()
//super("Chat Client");
getContentPane().setLayout(new BorderLayout());
output = new TextArea();
// Panel to arrange two components on
Panel p = new Panel();
p.setLayout(new BorderLayout());
input = new TextField();
b= new Button("Send");
// What happens when we press the button...
b.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e)
// read in text from textField, store as string
message = input.getText();
out.println(message);
System.out.println("Message is:" + message);
//out.flush(); We set the boolean autoflush to true in constructor
// blank the textField for next line
input.setText(" ");
}); // ends inner class
// add the textfield and button to the Panel
p.add("North", input);
p.add("South", b);
// add the textArea and the Panel to the Frame
getContentPane().add("Center", output);
getContentPane().add("South", p);
// the 'engine' behind the GUI
public void runClient()
// set hostname to 127.0.0.1 for testing
hostname="localhost";
// try to create the socket and initialise the Streams
try
Socket s = new Socket(hostname,9999);
in = new BufferedReader(new InputStreamReader(s.getInputStream()));
out = new PrintWriter(s.getOutputStream(),true);
output.append("Connected to Server...\n");
catch(UnknownHostException e)
System.err.println(e);
catch(IOException e)
System.err.println(e);
// initialise a listener thread to catch messages from server
listener = new Thread(this);
listener.start();
System.out.println("Listener started");
// listener.start() creates a thread which calls run()
public void run()
// just loop reading the input stream
try
while(true)
String line = in.readLine();
System.out.println("Received from Server:" + line);
output.append(line + "\n");
catch(IOException e)
System.err.println(e);
// when the Thread is killed...
finally
listener = null;
input.setText(" ");
out.close();
public static void main(String args[])
chatClient c = new chatClient();
c.runClient();
Can someone show me the way?

Answer 1

Yes positiv this is how my server looks try for your self :
import java.net.*;
import java.io.*;
import java.util.*; /* we need a vector to handle unknown numbers of connections */
public class chatServer
public chatServer() throws IOException
/* we're not too bothered about the exception details, so
we'll acknowledge it here instead of writing lines of
code to analyse it */
// initialise new ServerSocket
ServerSocket s = new ServerSocket(9999);
// loop listening for connections and instantiate a new handler for each one
while(true)
Socket client = s.accept();
System.out.println("Accepted connection from " + client.getInetAddress()+":"+ client.getPort());
chatHandler c = new chatHandler(client);
c.start(); // chatHandler is derived from Thread, so we can call start()
public static void main(String[] args) throws IOException
chatServer cs = new chatServer();
} // end class definition
// define class chatHandler as a derivation of Thread
class chatHandler extends Thread
// declare variables
protected Socket s;
protected BufferedReader in;
protected PrintWriter out;
protected static Vector handlers = new Vector();
public chatHandler(Socket s) throws IOException
// assign socket passed to object to class variable s
this.s = s;
// initialise streams
in = new BufferedReader(new InputStreamReader(s.getInputStream()));
out = new PrintWriter(s.getOutputStream(), true);
     System.out.println("Readers and Writers initialised");
public void run()
System.out.println("run called");
try
// add this thread to class variable vector
handlers.addElement(this);
          System.out.println("Element added to Vector");
// loop reading input and passing it to broadcast method
while(true)
               System.out.println("About to read inputstream");
String message = in.readLine();
               System.out.println("Input Stream read");
               System.out.println(message);
broadcast(message);
               System.out.println("Message passed to broadcast method");
catch(IOException e)
System.err.println(e);
// if this thread is killed....
finally
// remove it from the vector
handlers.removeElement(this);
try
// tidy up debris!
s.close();
catch(IOException e)
System.err.println(e);
// this static method is used by all threads
protected static void broadcast(String message)
/* to prevent two threads trying to access the vector
simultaneously we use a synchronized block */
     System.out.println("Broadcast called");
synchronized(handlers)
/* The Enumeration interface gives us a quick way of looking at
a vector which by definition is an unknown length */
Enumeration e = handlers.elements();
// returns true if there are other sockets running
while (e.hasMoreElements())
// loop to the next chatHandler in the vector
chatHandler c = (chatHandler) e.nextElement();
// write the message to it
try
/* prevent two threads trying to write
to the stream c.out */
synchronized(c.out)
c.out.println(message);
} // end synchronized block
//c.out.flush(); we set the boolean autoflush to true in the constructor
catch(Exception ex)
System.err.println(ex);
// explicitly stop the thread if exception is thrown
c = null;
} // end while loop
} // end synchronized block
} // end broadcast
} // ends class