Java org.jdom2.IllegalAddException:内容已存在父级

我正在尝试将新的xml数据添加到现有的xml文件中。但我得到了这个错误。 我尝试添加一个新的类型，我在原始文件中已经得到了大约20个

 Exception in thread "AWT-EventQueue-0" org.jdom2.IllegalAddException: The Content already has an existing parent "type"
    at org.jdom2.ContentList.checkPreConditions(ContentList.java:211)
    at org.jdom2.ContentList.add(ContentList.java:244)
    at org.jdom2.ContentList.add(ContentList.java:79)
    at java.util.AbstractList.add(Unknown Source)
    at org.jdom2.Element.addContent(Element.java:917)
    at xmleditor.service.CreateNewXMLData.saveXmlToFile(CreateNewXMLData.java:64)
    at xmleditor.gui.CreateNewObjectType$1.actionPerformed(CreateNewObjectType.java:405)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

public void saveXmlToFile（类型为objType，属性为Properties） 抛出IOException、ParserConfiguration异常、SAXException、， JDOMException{

        File xmlFile = new File("xmlFiles/CoreDatamodel.xml");
        org.jdom2.Document doc = new SAXBuilder().build(xmlFile);
        Element root = doc.getRootElement().clone();
        root.detach();

        root.setNamespace(Namespace.NO_NAMESPACE);
        Element type = new Element("type");
        Element prop = new Element("prop");
        root.addContent(type);
        prop.setNamespace(Namespace.NO_NAMESPACE);
        type.setNamespace(Namespace.NO_NAMESPACE);

        type.addContent(new Element("OBJECT_TYPE").setText(objType
                .getObjectType()));
        type.addContent(prop);

        prop.addContent(new Element("DESCRIPTION").setText(property
                .getDescription()));
        prop.addContent(new Element("PARENT").setText(property.getParent()));
        prop.addContent(new Element("VIRTUAL").setText(property.getVirtual()));
        prop.addContent(new Element("VISIBLE").setText(property.getVisible()));
        prop.addContent(new Element("PICTURE").setText(property.getPicture()));
        prop.addContent(new Element("HELP").setText(property.getHelp()));
        prop.addContent(new Element("MIN_NO").setText(property.getMin_no()));
        prop.addContent(new Element("MAX_NO").setText(property.getMax_no()));
        prop.addContent(new Element("NAME_FORMAT").setText(property
                .getName_format()));
        prop.addContent(prop);

        XMLOutputter xmlOutput = new XMLOutputter(Format.getPrettyFormat());
        // Create a new file and write XML to it
        xmlOutput.output(doc, new FileOutputStream(new File(
                "xmlFiles/CoreDatamodel.xml")));
        System.out.println("Wrote to file");
}

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如何解决此问题？

删除

prop.addContent（prop）

下面的代码块创建根元素的克隆并将其分离

org.jdom2.Document doc = new SAXBuilder().build(xmlFile);
Element root = doc.getRootElement().clone();
root.detach();

这就是您的文档未更新的原因。有两个选项：

尝试使用克隆的根目录创建新文档，并将其写入文件

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将内容添加到现有根元素

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希望这有帮助。

检查'prop.addContent（prop）；'这是怎么回事？我的代码中已经有了它……它消除了错误，但文件没有更新“将内容添加到现有的根元素”：root.addContent（prop）；给出了与早期相同的错误Yeh，现在已经开始工作了。只需要删除事情的顺序