Blackberry: display Alert/Status/Dialog early and exit

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 dis开发者_高级运维play 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;
        }
    }
}

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()

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);
        }
    }
}