public static void main(String args[]) {
        Principal2 frame = new Principal2();  
        frame.setExtendedState(frame.getExtendedState()|JFrame.MAXIMIZED_BOTH);  
        //frame.setVisible(true);  
        
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Principal2().setVisible(true);
            }
        });
    }