Problem update JTextArea with message from thread

Question

I have a JTextArea to present the actually status of an running thread. The thread sends strings like: System.out.println("Reading in new message...");to the standardoutput.
The problem is, that my application freezes when it should update the JTextArea. Any idea and what type of actionListener is recommend to use for the JTextArea?
try
   BufferedReader breader = new BufferedReader(new InputStreamReader(System.in));
   statusmsg = breader.readLine();
   statusTextArea.append(statusmsg);
catch (Exception e){};Cheers

Answer 1

In general, you can't update the Swing stuff from "side" threads. Side threads talk with the Swing event thread by creating Runnable objects which contains the necessary data (in your case, for instance, the JTextArea or its parent panel/window, and the text to append), and then invoking SwingUtilities.invokeLater() to have this object run() method called by the Sing event thread. See:
http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html