import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Comment;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
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"));
// Find all elements with the name "entry" and append a comment
NodeList list = doc.getElementsByTagName("entry");
for (int i = 0; i < list.getLength(); i++) {
Element element = (Element) list.item(i);
Comment comment = doc.createComment("index=" + i);
// Add the comment after this element
element.getParentNode().insertBefore(comment, element.getNextSibling());
}
}
}