如果(U→1)
{
final JFrame frame = new JFrame("multiple pagetable changes!!!");
frame.setLocationByPlatform(true);
final JOptionPane pane1= new JOptionPane(change_log);
final JDialog d1 = pane1.createDialog(frame,"");
d1.pack();
d1.setLocationRelativeTo(null);
d1.setVisible(true);
}