如何从主类加载Java GUI类？

public static void main(String[] args) {        SwingUtilities.invokeLater(new Runnable() {        public void run() { FileExtractorGUI gui = new FileExtractorGUI(); Jframe frame = new Jframe(); frame.setDefaultCloseOperation(Jframe.EXIT_ON_CLOSE); frame.getContentPane().add(gui); frame.pack(); frame.setVisible(true);        }    });}