Java tutorial
import java.io.File; import javax.xml.parsers.DocumentBuilderFactory; import org.w3c.dom.Comment; import org.w3c.dom.Document; import org.w3c.dom.Element; public class Main { public static void main(String[] argv) throws Exception { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); factory.setValidating(true); factory.setExpandEntityReferences(false); Document doc = factory.newDocumentBuilder().parse(new File("filename")); Element element = doc.getElementById("key1"); element = doc.createElement("root"); doc.appendChild(element); element.insertBefore(doc.createTextNode("A"), element.getFirstChild()); } }