如何在Java中使用DOM在XML文档中的相同层次结构级别上添加两个或多个相同名称的元素

Question

I've been trying to create an XML document in Java using DOM where there are multiple car elements of the same name on the same hierarchical level, similar to the following:

<Root>
  <Car>
    <Make>Ford</Make>
    <Model>Fiesta</Model>
  </Car>
  <Car>
    <Make>VW</Make>
    <Model>Golf</Model>
  </Car>
</Root>

However, during construction of the XML, whenever I attempt to add another Car element, it seems to override the one that is already there, resulting in me only getting one Car element in my output.

I create the car element using the following code:

Element carElement = doc.createElement("Car");

And then attempt to append to the first Car element that I create using the following code:

root.appendChild(carElement);

I have also tried the following code to no avail:

Node existingCar = doc.getElementsByTagName("Car").item(0);
existingCar.getParentNode().insertBefore(carElement, existingCar);

The Java docs state that for both the appendChild() and insertBefore() methods, if the newChild node exists, then it will firstly be removed - hence why I think Im only seeing one output in my XML.

Therefore, can someone confirm whether or not this is possible with DOM? If so, can they please advise or point me in the direction of a solution? Thanks

Answer 1

I can confirm that this is possible with DOM!

You haven't shown us your actual code where you try to add more than one child element with the same name, so we cannot tell you exactly why it doesn't work. However, maybe this snippet will give you a hint of how to fix your code. To add five Car elements:

    DocumentBuilder b = ...;

    DOMImplementation impl = b.getDOMImplementation();
    Document d = impl.createDocument(null, "Root", (DocumentType) null);
    Element root = d.getDocumentElement();
    for (int i = 0; i < 5; ++i) {
        Element car = d.createElement("Car");
        // add sub-elements/attributes to car element
        ...
        root.appendChild(car);
    }