JInternalFrame去掉标题栏后，怎么最小化

JInternalFrame去掉标题栏后，如何最小化
我用((BasicInternalFrameUI)getUI()).setNorthPane(null)这个方法将标题栏去掉后，如何在不恢复标题栏的情况下，实现最小化操作？

[解决办法]

Java code

public void setIcon(boolean b)             throws PropertyVetoExceptionIconifies or de-iconifies this internal frame, if the look and feel supports iconification. If the internal frame's state changes to iconified, this method fires an INTERNAL_FRAME_ICONIFIED event. If the state changes to de-iconified, an INTERNAL_FRAME_DEICONIFIED event is fired.