我发现了这个问题的答案。方法如下：
我创建了另一个层次结构层，
<userList>每次迭代for循环时，我都会使新创建
<user>的子层为
<userList>。
最后，超出了for循环的范围，我
<userList>将xml文档作为整个子文档。
这是那些有兴趣的新代码。您可以阅读
createDoc()方法中的注释，以帮助弄清楚我在上面解释的内容：
public class XMLwriter {private ArrayList<String> names;private document doc;private Random rand;private ArrayList<Element> users;public XMLwriter() throws ParserConfigurationException, TransformerException{ documentBuilderFactory docFactory = documentBuilderFactory.newInstance(); documentBuilder docBuilder = docFactory.newdocumentBuilder(); doc = docBuilder.newdocument(); rand = new Random(); users = new ArrayList<Element>(); names = new ArrayList<String>(); names.add("Ralph Wiggum");names.add("Mr. Hanky");names.add("Bulbasaur"); names.add("Tyroil Smoochie Wallace");names.add("Scooby Doo");names.add("Neville Longbottom"); names.add("Jabba the Hutt");names.add("Silky Johnson");names.add("Master Chief"); names.add("Frodo Baggins");names.add("Clayton Bigsby");names.add("John Snow"); names.add("Eric Cartman");names.add("Leoz Maxwell Jilliumz");names.add("Aslan"); createDoc(); generateFile();}public void createDoc(){ Element userList = doc.createElement("userList");//here, I create a new, over-arching element. for(int k = 0; k < names.size(); k++) { users.add(doc.createElement("user")); } for (int x = 0; x < 2; x++){ //create the elements Element record = doc.createElement("record"); users.get(x).appendChild(record); userList.appendChild(users.get(x));//I make each of the <user> elements a child of the over-arching element //The line that was throwing the error //create the attributes Attr name = doc.createAttribute("name"); Attr date = doc.createAttribute("date"); Attr project = doc.createAttribute("project"); Attr time = doc.createAttribute("time"); Attr id = doc.createAttribute("id"); //give all of the attributes values name.setValue(names.get(x)); date.setValue(new Date().toString()); project.setValue("Project" + (rand.nextDouble() * 1000)); time.setValue("" + rand.nextInt(10)); id.setValue("" + (rand.nextDouble() * 10000)); //assign the attributes to the elements users.get(x).setAttributeNode(name); record.setAttributeNode(date); record.setAttributeNode(project); record.setAttributeNode(time); record.setAttributeNode(id); } doc.appendChild(userList);//note how I append this child outside of the for loop}public void generateFile() throws TransformerException{ TransformerFactory transformerFactory = TransformerFactory.newInstance(); Transformer transformer = transformerFactory.newTransformer(); DOMSource source = new DOMSource(doc); StreamResult result = new StreamResult(new File("C:\Users\sweidenkopf\workspace\test\testxml.xml")); // Output to console for testing // StreamResult result = new StreamResult(System.out); transformer.setOutputProperty(OutputKeys.INDENT, "yes"); transformer.setOutputProperty("{http://xml.apache.org/xslt}indent-amount", "2"); transformer.transform(source, result);}}
