Java HTML/XML - 如何將Text對象添加到元素

import java.io.StringReader;
  import java.io.StringWriter;

  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.transform.Transformer;
  import javax.xml.transform.TransformerException;
  import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;

  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.NamedNodeMap;
  import org.w3c.dom.Node;
  import org.xml.sax.InputSource;

  public class Main {
    public static String getXMLData() {
      return "<a attr='value'></a>";
    }

    public static void main(String[] argv) throws Exception {
      DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
      Document doc = factory.newDocumentBuilder().parse(
          new InputSource(new StringReader(getXMLData())));

      addText(doc.getDocumentElement(),"new text");

      System.out.println(documentToString(doc));

    }
    public static void addText(Element element, String text) {
      element.appendChild(element.getOwnerDocument().createTextNode(text));
    }

    public static String documentToString(Document document) {
      try {
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer trans = tf.newTransformer();
        StringWriter sw = new StringWriter();
        trans.transform(new DOMSource(document), new StreamResult(sw));
        return sw.toString();
      } catch (TransformerException tEx) {
        tEx.printStackTrace();
      }
      return null;
    }
  }