Java XML Element append child

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
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.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

public class Main {
   public static void main(String args[]) {
      try {//  w w  w  .j ava2s .  c o m
         DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
         DocumentBuilder parser = factory.newDocumentBuilder();
         Document doc = parser.parse("questions.xml");
         Element root = doc.getDocumentElement();

         TransformerFactory tFactory = TransformerFactory.newInstance();
         Transformer transformer = tFactory.newTransformer();
         DOMSource source = new DOMSource(root);
         StreamResult result = new StreamResult(System.out);

         transformer.transform(source, result);

         NodeList questions = doc.getElementsByTagName("question");
         Node aCopy = questions.item(0).cloneNode(true);
         ((Element) aCopy).setAttribute("id", "q3");
         ((Text) aCopy.getFirstChild()).replaceWholeText("What is XML?");
         root.appendChild(aCopy);

         transformer.transform(source, result);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}