javax.xml.bind.Binder.updateJAXB() Method

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Description

The Javax.xml.bind.Binder.updateJAXB(XmlNode xmlNode) method takes an XML node and updates its associated JAXB object and its descendants.

This operation can be thought of as an "in-place" unmarshalling. The difference is that instead of creating a whole new JAXB tree, this operation updates an existing tree, reusing as much JAXB objects as possible.

Declaration

Following is the declaration for javax.xml.bind.Binder.updateJAXB(XmlNode xmlNode) method

public abstract Object updateJAXB(XmlNode xmlNode)

Parameters

xmlNode − the document/element to unmarshal XML data from.

Return Value

Returns the updated JAXB object.

Exception

• JAXBException − if any unexpected error occur while unmarshalling.

• IllegalArgumentException − If the node parameter is null.

Example

The following example shows the usage of javax.xml.bind.Binder.updateJAXB(XmlNode xmlNode) method. To proceed, consider the following Student class which will be used to have objects for "in-place" unmarshalling purpose −

package com.tutorialspoint;

import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
 
@XmlRootElement
public class Student{
 
   String name;
   int age;
   int id;

   public String getName(){
      return name;
   }

   @XmlElement
   public void setName(String name){
      this.name = name;
   }

   public int getAge(){
      return age;
   }

   @XmlElement
   public void setAge(int age){
      this.age = age;
   }

   public int getId(){
      return id;
   }

   @XmlAttribute
   public void setId(int id){
      this.id = id;
   }
}

Now let us create main class which will be used to unmarshal ie. convert Student XML file to JAXB object. Here we will creat Binder object using JAXBContext because we can not create Binder object directly because it is an abstract class. This example unmarshals the Student.xml to JAXB object.

package com.tutorialspoint;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Binder;
import javax.xml.bind.Marshaller;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;

public class BinderDemoUnmarshall {
   public static void main(String[] args) {

      try {
         // we need a document to store Student.xml as input
         DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
         DocumentBuilder docBuilder = dbf.newDocumentBuilder();
         Document document = docBuilder.parse("Student.xml");
          
         // create JAXBContext which will be used to create a Binder
         JAXBContext jc = JAXBContext.newInstance(Student.class);

         // create binder
         Binder<Node> binder = jc.createBinder();
         
         // get xml node from the document
         Node xmlNode = document.getDocumentElement();
         
         // Returns the updated JAXB object
         Student st = (Student)binder.updateJAXB(xmlNode);
         
         // print
         System.out.println("Age: "+st.getAge());
         System.out.println("Name: "+st.getName());
    
      }catch(Exception ex) {
         ex.printStackTrace();
      }
   }
}

To create document, an XML file is needed as input. The XML file is named as Student.xml−

<?xml version = "1.0" encoding = "UTF-8" standalone = "no"?>
<student id = "10">
   <age>10</age>
   <name>Zara Ali</name>
</student>

Before we proceed for compilation, we need to make sure that that we download JAXB2.xxx.jar and put it in our CLASSPATH. Once setup is ready, let us compile and run the above program, this will produce the following result −

Age: 10
Name: Zara Ali