Repaint in Java application (not Applet)

Question

Hi,
I have server application with GUI containing TextArea. On any connection request from client, the application creates a thread which deals with the client request. Once the client request finishes, I want to show the detail of the client which connected to the server in the TextArea. Now I have extended the main server class for the thread class, which deals with the client, and have a method in the main server class which appends string on the textarea. BUT, when thread call that function nothing appears in the TextArea. I have checked that the thread is calling the method correctly, I think I need to repaint the TextArea. How? I am looking for your help. I have tried repaint, it does not work. Appreciate any help in this regard,
Here is the code.
Server side.......
public synchronized void displayMessage( String thismessage) {
     System.out.println("-----> " + thismessage);
     editPan.setEditable(true);
     editPan.append(thismessage + "\n");
public void run() {
while(true) {
try {
server = new ServerSocket( 5000, 100 );
while(listening) {
connection = server.accept();
if(connection != null) {
alertDialog cThread = new alertDialog(connection, errorNumber);
(new Thread(cThread)).start();
errorNumber++;
connection = null;
catch( IOException e ) {
System.out.println("Exception : " + e.toString() );
Client Attender Thread class (alertDialog) which extends server class......
public void run() {
try {
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String inputLine = in.readLine();
System.out.println(" " + dateString + " " + inputLine );
// super.editPan.append(" Test from alert.. \n");
     super.displayMessage(" " + dateString + " " + inputLine);
JOptionPane.showMessageDialog(null, inputLine, "Alert....", JOptionPane.ERROR_MESSAGE);
in.close();
} catch (IOException e) {

Answer 1

Be careful when calling Swing methods from outside the EventDispatch thread. If you call a swing method from a thread, you should use SwingUtilities.invokeAndWait() or SwingUtilities.invokeLater().
See http://java.sun.com/docs/books/tutorial/uiswing/mini/threads.html for more details.