Here is an example that appends a new node to the existing xml document. Here is an xml file where we are going to append a new node.

<?xml version="1.0" encoding="UTF-8" standalone="no"?><school>
<student>
<name>Angelina</name>
<address>Delhi</address>
</student>
<student>
<name>Martina</name>
<address>Mumbai</address>
</student>
</school>

Here is a code that appends a new node student with name and address elements.

import java.io.*;
import org.w3c.dom.*;
import javax.xml.parsers.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.*;
import javax.xml.transform.stream.*;

public class AppendNode {

    public static void main(String[] args) {
        try {
            File xmlFile = new File("C:\\file.xml");
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
            DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
            Document document = documentBuilder.parse(xmlFile);
            Element documentElement = document.getDocumentElement();
            Element textNode = document.createElement("name");
            textNode.setTextContent("Rose");
            Element textNode1 = document.createElement("address");
            textNode1.setTextContent("Delhi");
            Element nodeElement = document.createElement("student");
            nodeElement.appendChild(textNode);
             nodeElement.appendChild(textNode1);
            documentElement.appendChild(nodeElement);
            document.replaceChild(documentElement, documentElement);
            Transformer tFormer =
                    TransformerFactory.newInstance().newTransformer();
            tFormer.setOutputProperty(OutputKeys.METHOD, "xml");
            Source source = new DOMSource(document);
            Result result = new StreamResult(xmlFile);
            tFormer.transform(source, result);


        } catch (Exception ex) {
            System.out.println(ex);
        }
    }
}