Update TextArea from thread

I have one panel class called ITKstartProfile where I added my TextArea on the Panel.

At the and of the Panel logic I start a Thread with a ITKInformationThread class

    ITKInformationThread informationThread = new ITKInformationThread(editor) ;

public class ITKInformationThread extends Thread {
TextArea text = null;
long i = 0;

ITKInformationThread(TextArea t) {
	text = t;

public void run() {

	while (true) {
		text.setValue("thread" + i + "\n");
		try {
		} catch (InterruptedException e) {



When I do a System.err.print I see the variable I counting.
On my TextArea the values are not updated or added. I only see the first time thread0 but the thread1, thread2 etc are not displayed.

What do I wrong here?

Is it not possible to add information in a TextArea from a separate thread?


First: You need to synchronize on the Application-instance any time you update the UI from a background-thread.

Second: The server cannot trigger an update towards the client (as long you are not using special addons like IcePush). So probably the textarea
updated - but only on the server-side were no one ever sees it. To check this you can add for example a Button to your UI and click it after your thread ended. If the situation I just explained applies, you will suddenly see your changes afterwards ;). To get around this you will need to use IcePush, Refresher, a ProgressIndicator or my addon VaadinWorker.