dom 4 jポイントを使用して要素ノードを挿入する

Document doc=SemanticPluginItems.loadXmlFile("D:\\      (  )\\Administrator\\  \\11.xml");
		Element root=doc.getRootElement();
		List<Element> l=root.content();//          
		List<Element> l2=doc.selectNodes("//child");//      child     
		Element e = DocumentHelper.createElement("child");//    child  		
                     e.addAttribute("name","ddddddddd");//        
		l.add(l.indexOf(l2.get(0)), e);//             child   
		root.setContent(l);//        
		OutputFormat format = OutputFormat.createPrettyPrint();   
        format.setEncoding("UTF-8");   
        XMLWriter writer = new XMLWriter(new FileWriter("D:\\      (  )\\Administrator\\  \\11.xml"),format);   
        writer.write(doc);   
        writer.close();