Insert a comment in front of the element node : Comment « XML « Java Tutorial

1. Java Tutorial
2. XML
3. Comment

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);

    Comment comment = doc.createComment("a comment");
    doc.insertBefore(comment, element);

  }
}