Xml

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.File;
import java.io.OutputStream;
import java.io.StringWriter;
import org.w3c.dom.*;
import javax.xml.parsers.*; 
import javax.xml.transform.*; 
import javax.xml.transform.dom.DOMSource; 
import javax.xml.transform.stream.StreamResult; 
import org.xml.sax.SAXException;
 
public class modifyXML {
   public static void main(String args[]) {
     try {	
	File file = new File("connections.xml");
 
	//Create instance of DocumentBuilderFactory
	DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
 
	//Get the DocumentBuilder
	DocumentBuilder docBuilder = factory.newDocumentBuilder();
 
	//Using existing XML Document
	Document doc = docBuilder.parse(file);
 
	//create the root element
	Element root = doc.getDocumentElement();
 
	//create child element
	Element childElement = doc.createElement("number");
 
        //Add the attribute to the child
	childElement.setAttribute("id","3");
	root.appendChild(childElement);
 
	//set up a transformer
	TransformerFactory transfac = TransformerFactory.newInstance();
	Transformer trans = transfac.newTransformer();
 
        //create string from xml tree
        StringWriter sw = new StringWriter();
        StreamResult result = new StreamResult(sw);
        DOMSource source = new DOMSource(doc);
        trans.transform(source, result);
        String xmlString = sw.toString();
 
        OutputStream f0;
	byte buf[] = xmlString.getBytes();
	f0 = new FileOutputStream("connections.xml");
	for(int i=0;i<buf .length;i++) {
	   f0.write(buf[i]);
	}
	f0.close();
	buf = null;
     }
     catch(SAXException e) {
	e.printStackTrace();		
     }
     catch(IOException e) {
        e.printStackTrace();		
     }
     catch(ParserConfigurationException e) {
       e.printStackTrace();		
     }
     catch(TransformerConfigurationException e) {
       e.printStackTrace();		
     }
     catch(TransformerException e) {
       e.printStackTrace();		
     }
  }
}

< ?xml version="1.0" encoding="UTF-8"?>
     <connection>
	<number id="1"/>	
	<number id="2"/>	
     </connection>