java如何管理调用另一个JInternalFrame的JInternalFrame？

我有一个带有此代码的JDesktopPane.

public class Menu extends JFrame implements ActionListener{
/**
* Creates new form Portada
*/
public static JDesktopPane desktop;
public JDesktopPane getDesktop() {
return desktop;
}
public Menu() {
desktop = new JDesktopPane();
setContentPane(desktop);
desktop.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);
initComponents();
}
}


然后我像这样添加新组件

desktop.add(orden);


当我想给他们打电话时

if(e.getSource()==jMenuItem1_1){
orden.setVisible(true);
desktop.setSelectedFrame(orden);
desktop.moveToFront(orden);
try {
orden.setSelected(true);
} catch (PropertyVetoException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}


我得到的问题是,当“ orden”想要弹出另一个JInternalFrame时,我将使用下一个代码.

searchSupplier.setVisible(true);
Main.getInstance().getPortada().getDesktop().add(searchSupplier);
Main.getInstance().getPortada().getDesktop()
.moveToFront(searchSupplier);
try {
searchSupplier.setSelected(true);
} catch (PropertyVetoException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}


当我执行事件超过2次时,出现下一个错误：

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: illegal component position


我应该在哪里将新的JInternalFrame添加到DesktopPane？或到Orden ？,或该如何解决此错误？

解决方法:

如果searchSupplier框架已经在桌面上,则不太可能再次添加它.尝试使用getParent确定是否需要添加框架

if (searchSupplier.getParent() == null) {
Main.getInstance().getPortada().getDesktop().add(searchSupplier);
}
searchSupplier.setVisible(true);
Main.getInstance().getPortada().getDesktop().moveToFront(searchSupplier);
try {
searchSupplier.setSelected(true);
} catch (PropertyVetoException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}