添加Jinternalframe时java组件位置非法

Question

我试图运行以下代码，但它给了我一个错误

public void addToContainer(JInternalFrame internalframe){
    JInternalFrame []allFrames = Jdpmain.getAllFrames();//getting an array of all the frames in my jdesktoppane(jdpmain)
    boolean flag=false;
    for(int i=0;i<allFrames.length;i++){
        JInternalFrame currentFrame = allFrames[i];
        if(internalframe.getClass().isInstance(allFrames[i])){
            Jdpmain.setSelectedFrame(currentFrame);//if the internal frame already exist it might be under another jinternalframe so, I called this method to bring it to focus
            flag=true;
        }
        if(flag==false){
            Jdpmain.add(internalframe); //if an instance of the frame I am adding does not exist in jdesktoppane it should add an instance of it to jdesktoppane   
        } 
    }
}

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: illegal component position at java.awt.Container.addImpl(Container.java:1093) at javax.swing.JLayeredPane.addImpl(JLayeredPane.java:230) at javax.swing.JDesktopPane.addImpl(JDesktopPane.java:486) at java.awt.Container.add(Container.java:410) at MyLibrarypackage.MainFrame.addToContainer(MainFrame.java:169) at MyLibrarypackage.MainFrame.jButton2ActionPerformed(MainFrame.java:148) at MyLibrarypackage.MainFrame.access$100(MainFrame.java:13) at MyLibrarypackage.MainFrame$2.actionPerformed(MainFrame.java:62) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252) at java.awt.Component.processMouseEvent(Component.java:6505) at javax.swing.JComponent.processMouseEvent(JComponent.java:3321) at java.awt.Component.processEvent(Component.java:6270) at java.awt.Container.processEvent(Container.java:2229) at java.awt.Component.dispatchEventImpl(Component.java:4861) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422) at java.awt.Container.dispatchEventImpl(Container.java:2273) at java.awt.Window.dispatchEventImpl(Window.java:2713) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707) at java.awt.EventQueue.access$000(EventQueue.java:101) at java.awt.EventQueue$3.run(EventQueue.java:666) at java.awt.EventQueue$3.run(EventQueue.java:664) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:680) at java.awt.EventQueue$4.run(EventQueue.java:678) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:677) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105) at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

如果有人能帮我，我会很高兴的