import org.w3c.dom.Document; import org.w3c.dom.Element; public class DOMParser { public static void main(String[] args) { Document document = parseXML("example.xml"); Element root = document.getDocumentElement(); Element element = root.getElementsByTagName("item").item(0); int index = getElementIndex(element); System.out.println("Index of element: " + index); } private static Document parseXML(String fileName) { // code for parsing XML file omitted } private static int getElementIndex(Element element) { Element parent = (Element) element.getParentNode(); int index = 0; while (parent.getChildNodes().item(index) != element) { index++; } return index; } }In this example, we parse an XML file and retrieve the first "item" element in the document. We then pass this element to the getElementIndex method to determine its index within its parent element. The result is printed to the console. The package library for this method is org.w3c.dom.