import sun.lwawt.LWWindowPeer;

import javax.swing.*;
import java.awt.*;

public class Test {
    static Frame window = null;
    static Point pt = null;
    public static void main(String args[]) {
        try {
            EventQueue.invokeAndWait(() -> {
                window = new Frame();
                window.setUndecorated(true);
                window.add(new JButton());
                window.setSize(300,300);
                int dx = 0, dy = 0;
                GraphicsConfiguration gc = window.getGraphicsConfiguration();
                Rectangle gcBounds = gc.getBounds();
                Dimension windowSize = window.getSize();
                gcBounds = gc.getBounds();
                dx = gcBounds.x + (gcBounds.width - windowSize.width) / 2;
                dy = gcBounds.y + (gcBounds.height - windowSize.height) / 2;
                window.setLocation(dx, dy);
                window.setVisible(true);
            });

            try { Thread.sleep(3000); } catch (Exception e) {}

            EventQueue.invokeAndWait(() -> {
                pt = window.getLocationOnScreen();
            });

            System.out.println(window);
            System.out.println(((LWWindowPeer)window.getPeer()).getBounds());
            System.out.println(pt);
        }catch(Exception exx) {
        }
    }
}