How To Modify XML File In Java – (DOM Parser)

In this example, we demonstrate the use of DOM parser to modify an existing XML file :

1. Add a new element


2. Update existing element attribute


3. Update existing element value


4. Delete existing element

1. XML file

See before and after XML file.

File : file.xml – Original XML file.

 
VD.
<!--?xml version="1.0" encoding="UTF-8" standalone="no" ?> 

	yong
	mook kim
	mkyong
	100000

Later, update above XML file via DOM XML Parser.

1. Update the staff attribute id = 2


2. Update salary value to 200000


3. Append a new “age” element under staff


4. Delete “firstname” element under staff

File : file.xml – Newly modified XML file.

VD.
 

	mook kim
	mkyong
	2000000 
        28

2. DOM Parser

DOM XML parser to update an above XML file.

import java.io.File;
import java.io.IOException;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class ModifyXMLFile {

	public static void main(String argv[]) {

	   try {
		String filepath = "c:\\file.xml";
		DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
		DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
		Document doc = docBuilder.parse(filepath);

		// Get the root element
		Node company = doc.getFirstChild();

		// Get the staff element , it may not working if tag has spaces, or
		// whatever weird characters in front...it's better to use
		// getElementsByTagName() to get it directly.
		// Node staff = company.getFirstChild();

		// Get the staff element by tag name directly
		Node staff = doc.getElementsByTagName("staff").item(0);

		// update staff attribute
		NamedNodeMap attr = staff.getAttributes();
		Node nodeAttr = attr.getNamedItem("id");
		nodeAttr.setTextContent("2");

		// append a new node to staff
		Element age = doc.createElement("age");
		age.appendChild(doc.createTextNode("28"));
		staff.appendChild(age);

		// loop the staff child node
		NodeList list = staff.getChildNodes();

		for (int i = 0; i < list.getLength(); i++) {

                   Node node = list.item(i);

		   // get the salary element, and update the value
		   if ("salary".equals(node.getNodeName())) {
			node.setTextContent("2000000");
		   }

                   //remove firstname
		   if ("firstname".equals(node.getNodeName())) {
			staff.removeChild(node);
		   }

		}

		// write the content into xml file
		TransformerFactory transformerFactory = TransformerFactory.newInstance();
		Transformer transformer = transformerFactory.newTransformer();
		DOMSource source = new DOMSource(doc);
		StreamResult result = new StreamResult(new File(filepath));
		transformer.transform(source, result);

		System.out.println("Done");

	   } catch (ParserConfigurationException pce) {
		pce.printStackTrace();
	   } catch (TransformerException tfe) {
		tfe.printStackTrace();
	   } catch (IOException ioe) {
		ioe.printStackTrace();
	   } catch (SAXException sae) {
		sae.printStackTrace();
	   }
	}
}