This is the main file for marshalling and unmarshalling the XML file.

ReadXml.java

package com.jaxb;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class ReadXml {
	
	public static void main(String[] args) throws IOException {
		File xmlFile = new File("ussd.xml");
		unmarshalXML(xmlFile);
		marshalXML();


}

//-------------------------- UNMARSHALLING XML  -------------------------------
public static void unmarshalXML(File xmlFile) {
    try {       
    System.out.println("Unmarshalling XML to Java Object-------");

    //creating the JAXB context
    JAXBContext jContext = JAXBContext.newInstance(USSDMenuRequest.class); 

     //create the unmarshal object
     Unmarshaller unmarshallerObj = jContext.createUnmarshaller();

     //call the unmarshal method
     USSDMenuRequest request= (USSDMenuRequest) unmarshallerObj.unmarshal(xmlFile);

    request.setStarCode("124");
    request.setKeyWord("Start");

  System.out.println(request.getShortCode() + " " + request.getPrompt() );
    }
    catch(Exception e){
            e.printStackTrace();
        }
    }
	
-------------------------- MARSHALLING XML  ----------------------------------
  public static void marshalXML() {
    try {       

    System.out.println("Marshalling Java Object to XML-------");

    //creating the JAXB context
        JAXBContext jContext = JAXBContext.newInstance(USSDMenuRequest.class); 

    //create the marshaller object
        Marshaller marshallerObj = jContext.createMarshaller();


        //the XML should be properly indented and formatted
    marshallerObj.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

    USSDDynMenuRequest Sendrequest= new USSDMenuRequest();

        Sendrequest.setShortCode("124");
        Sendrequest.setPrompt("Start");
    Sendrequest.setMessageid("0244708099");
    Sendrequest.setSessionId("789888886adh");


    //calling the marshall method
    marshallerObj.marshal(Sendrequest, new FileOutputStream("response.xml"));
        }
    catch(Exception e){
         e.printStackTrace();
            }
        }
}

ussd.xml

<?xml version="1.0" encoding="UTF-8"?>
<USSDDynMenuRequest>
<sessionId name='sessionId'>$sessionId</sessionId>
<messaged name='messageid'>$messageid</messageid>
<shortCode name='shortCode'>$shortCode</shortCode>
<prompt name='prompt'>$prompt</prompt>"
<menu>
		<value>param1</value>
		<value>param2</value>
		<value>param3</value>
</menu>
<userData name="name">$name</userData>
<timeStamp>$timestamp</timeStamp>
</USSDMenuRequest>

USSDMenuRequest.java

package com.jaxb;

//import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;



@XmlRootElement(name="USSDMenuRequest")
public class USSDMenuRequest{


    private  String sessionId;
    private  String messageid;
    private  String shortCode;
    private   String prompt;
    private   String timeStamp;





    @XmlElement(name="sessionId")
    public void setSessionId(String sessionId){
        this.sessionId = sessionId;
    }

     public String getSessionId(){
        return sessionId;
     }


  public String getMessageid(){
     return messageid;
}

    @XmlElement(name="messageid")
    public void setMessageid(String messageid){
        this.messageid = messageid;
}

    @XmlElement(name="shortCode")
    public void setShortCode(String shortCode){
        this.shortCode = shortCode;
}

    public String getShortCode(){
       return shortCode;
    }


    @XmlElement(name="prompt")
    public void setPrompt(String prompt){
        this.prompt = prompt;
}

    public String getKeyWord(){
       return keyWord;
}

   public String getTimeStamp(){
      return timeStamp;
   }


    }