Java DOM setAttribute不工作

有人能告诉我为什么这样不行吗？这快把我逼疯了

myFile.xml

<?xml version="1.0" encoding="UTF-8" ?>
<root date="oldValue" />     

输出

oldValue
oldValue

---

无论我做什么，我都无法让我的代码写入XML文件。。。我已经尝试在根节点的子节点上执行setAttribute（）函数。我试着移除根。。。什么都不管用。我非常沮丧，所以任何帮助都将不胜感激。谢谢。

您是否遵循与下面相同的代码？这适用于我（在myFile.xml中具有相同的内容）：

---

您的代码只是写入元素对象，而不是.xml文件（但是，当我运行代码时，我的输出是：

             date: oldValue

             date: test

要写入.xml文件，请使用以下命令

try
      {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(new File("myFile.xml"));

        Element root = doc.getDocumentElement();
        System.out.println("date: " + root.getAttribute("date") + "\n");
        root.setAttribute("date", "test");

        // write the content into xml file
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        DOMSource source = new DOMSource(doc);
        StreamResult result = new StreamResult(new File("myFile.xml"));
        transformer.transform(source, result);


        System.out.println("date: " + root.getAttribute("date"));

      }
    catch (TransformerException | SAXException | ParserConfigurationException | IOException e )
      {
        System.out.println("Something went wrong");
        e.printStackTrace();
      }

---

只是为了好玩，你在运行什么版本的Java？是的，我遵循相同的代码。这就是为什么它如此令人沮丧。我知道它能够访问文件，因为它可以很好地读取它。它只是不能写入它。我正在运行1.5。我有完全相同的问题。有人有解决方案吗？

             date: oldValue

             date: test

try
      {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        DocumentBuilder builder = factory.newDocumentBuilder();
        Document doc = builder.parse(new File("myFile.xml"));

        Element root = doc.getDocumentElement();
        System.out.println("date: " + root.getAttribute("date") + "\n");
        root.setAttribute("date", "test");

        // write the content into xml file
        TransformerFactory transformerFactory = TransformerFactory.newInstance();
        Transformer transformer = transformerFactory.newTransformer();
        DOMSource source = new DOMSource(doc);
        StreamResult result = new StreamResult(new File("myFile.xml"));
        transformer.transform(source, result);


        System.out.println("date: " + root.getAttribute("date"));

      }
    catch (TransformerException | SAXException | ParserConfigurationException | IOException e )
      {
        System.out.println("Something went wrong");
        e.printStackTrace();
      }