Blackberry: display Alert/Status/Dialog early and exit - blackberry

Question

Let's say I have a typical Blackberry app:
public class MyApp extends UiApplication {
public static void main(String[] args) {
MyApp app = new MyApp();
app.enterEventDispatcher();
}
public MyApp() {
pushScreen(new MyScreen());
}
}
and already at the beginning I notice, that a mandatory condition is missing (wrong Display dimensions; missing SD card; some IT policy; etc.)
Is there a way to display a short and quick message to the user (in the form of Alert/Status/Dialog/whatever) and exit straight away - without/before instantiating a complex Screen/registering Acceleration listeners/installing complex CleanupRunnable?
I've tried Status.show(), Dialog.alert() - they do not work (RuntimeException "pushModalScreen called by a non-event thread"):
public class MyScreen extends MainScreen {
public MyScreen() {
if (Display.getWidth() < 400) {
Status.show("Goodbye");
return;
}
}
}

Answer 1

Instead of direct invocation use invokeLater. Sample is below:
Application.getApplication().invokeLater(new Runnable() {
public void run() {
Dialog.inform("Your message here...");
}
});
Instead of Dialog.inform you may use Status.show()

Answer 2

Actually the following is better, than what's suggested by Rafael - because it doesn't have the ugly white screen underneath. Here is my complete example MyApp.java:
import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.ui.container.*;
import net.rim.device.api.ui.decor.*;
import net.rim.device.api.system.*;
import net.rim.device.api.ui.image.*;
public class MyApp extends UiApplication {
public static void main(String[] args) {
MyApp app = new MyApp();
app.enterEventDispatcher();
}
public MyApp() {
pushScreen(new MyScreen());
}
}
class MyScreen extends MainScreen implements DialogClosedListener {
Dialog myDialog = new Dialog(Dialog.OK, "Goodbye!", 0, Bitmap.getPredefinedBitmap(Bitmap.EXCLAMATION), Dialog.GLOBAL_STATUS);
public MyScreen() {
// XXX just some condition, like wrong dimensions or IT policy
if (Display.getWidth() > 40) {
myDialog.setDialogClosedListener(this);
Application.getApplication().requestBackground();
Application.getApplication().invokeLater(new Runnable() {
public void run() {
myDialog.show();
}
});
return;
}
// XXX heavy stuff to be skipped
}
public void dialogClosed(Dialog dialog, int choice) {
if (dialog == myDialog) {
System.out.println("XXX exiting XXX");
System.exit(1);
}
}
}