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POInvalid Thread Access Error with Java SWT
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copied!<p>I have a simple Java SWT app in Java so far but the weird thing is when I try to launch a messagebox/alert box upon listening to an event fired by one of my own classes, I get an error saying "Invalid thread access". </p> <p>My class event is fired and heard by the main class but it is when it has to show the MessageBox that the "Invalid thread access" error appear. I am trying to show the MessageBox in a function that consist of all the other codes that will create the SWT GUIs. This is how the function looks like: </p> <pre><code>public void createContents() { Shell shell = new Shell(); //.....all the SWT GUI codes.... MessageBox msg = new MessageBox(shell, SWT.OK); myClass.addEventListener(new MyClassEventClassListener() { @Override public void myClassEventHandler(MyClassEvent e) { msg.setText("Hello"); msg.setMessage("Event fired!"); int result = msg.open(); } }); } </code></pre> <p>These are the auxiliary functions together in the class.</p> <pre><code> protected static Shell shell; public static void main(String[] args) { MyClass new myClass = new MyClass(); try { SWTApp window = new SWTApp(); window.open(); } catch (Exception e) { } public void open() { Display display = Display.getDefault(); createContents(); shell.open(); shell.layout(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) { display.sleep(); } } } </code></pre> <p>The error stack trace is as follows:</p> <pre><code>Exception in thread "AWT-EventQueue-0" org.eclipse.swt.SWTException: Invalid thread access at org.eclipse.swt.SWT.error(SWT.java:4083) at org.eclipse.swt.SWT.error(SWT.java:3998) at org.eclipse.swt.SWT.error(SWT.java:3969) at org.eclipse.swt.widgets.Display.error(Display.java:1249) at org.eclipse.swt.widgets.Display.checkDevice(Display.java:755) at org.eclipse.swt.widgets.Display.getShells(Display.java:2171) at org.eclipse.swt.widgets.Display.setModalDialog(Display.java:4463) at org.eclipse.swt.widgets.MessageBox.open(MessageBox.java:200) </code></pre> <p>Any help will be great. Thanks!</p>

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