Marshalling and Unmarshalling in Java: Complete JAXB Guide with Examples

Marshalling and Unmarshalling in Java are important JAXB processes used to convert Java objects into XML and XML data back into Java objects. These techniques simplify data exchange between applications, improve interoperability, and reduce the complexity of handling XML data in Java projects.

JAXB (Java Architecture for XML Binding) provides an efficient way to map XML data to Java objects and vice versa. It is widely used in enterprise applications, web services, and system integrations where XML remains a common data format.

With JAXB, developers can easily marshal Java objects into XML documents and unmarshal XML documents back into Java objects without writing complex parsing code. JAXB also supports XML schema binding, making it easier to validate and manage structured data.

By simplifying XML processing, JAXB helps developers build cleaner, more maintainable, and scalable Java applications. In this guide, you will learn how Marshalling and Unmarshalling in Java work, the role of JAXB annotations, and practical examples for converting Java objects and XML data efficiently.

JAXB = Marshalling (Java Object → XML) + Unmarshalling (XML → Java Object).

What Is JAXB and Why Is It Important in Java?

Java for XML Binding, Use annotation pattern to convert java objects to or from XML. Here the two terms mostly used are Marshaling and Unmarshaling.

Marshalling in Java: Converting Java Objects to XML

By using a java object, create an xml file or convert a java object to xml.

Unmarshalling in Java: Converting XML Back to Java Objects

Create a java object again using an xml file.

Prerequisites:

• JDK 1.6
• JAXB 2

Note: If using jdk version less than 1.6, download JAXB from http://jaxb.java.net/, and copy “jaxb-api.jar” and “jaxb-impl.jar” and paste to your classpath.

No extra jaxb libraries are required if you are using JDK1.6 or above because it is bundled with jdk

Essential JAXB Annotations for XML Binding in Java

To convert things to/from XML using JAXB, use the Annotation pattern. We can apply a number of predefined annotation styles to our Java objects.

This annotation does not participate directly in the xml creation; rather, it supplies information about xml schema.

It has various properties like factoryClass, method, name, namespace, propOrder, and so on.

Below are some commonly used attributes –

name – Provides name to XML schema if you don’t want to use the class name

namespace – Provides the name of the target namespace (if you are using a reference object of some other class)

propOrder – Used to establish an ordering of the sub-elements

@XmlRootElement(name="TestDoc" )
@XmlType(propOrder = { "name", "stream", "class"})
public class TestingDocument
{
	String name;
	int class;
	String stream;
	
	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 String getStream() {
		return stream;
	}
 
	@XmlElement(name = "subject")
	public void setStream(String stream) {
		this.stream = stream;
	}	
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<TestDoc>
    <age></age>
    <subject></subject>
    <name></name>
</TestDoc>

• @XmlRootElement (name = “root”) :

  Top-level element class, Define root element of XML document. Its optional elements are name and namespace. By default, we used the class name as the name.

  @XmlRootElement(name="TestDoc" )
  public class TestingDocument
  {
  }

  After Marshaling of this java class, It will produced out put xml like –

  <?xml version="1.0" encoding="UTF-8"?><TestDoc>
  </TestDoc>

• @XmlType(propOrder = { “field2”, “field1”,”field3″….}) :
• @XmlElement(name = “test”)

Here is one more condition that I would like to explain here. Sometimes you need to define property with xml tab like in below xml property subjectType in subject tag-

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<TestDoc>
    <age>25</age>
    <subject subjectType="Math" >Science</subject>
    <name>testinguser</name>
</TestDoc>

public class Subject {
	@XmlValue
	private String Subject;
	@XmlAttribute(name = "subjectType", required = true)
	private String subjectType;
			
	public String getSubject() {
		return StandardPrice;
	}	
	
	public void setSubject(String value) {
		StandardPrice = value;
	}

	public void setSubjectType(String currency) {
		this.currency = currency;
	}	
	
	public String getSubjectType() {
		return currency;
	}			
}

@XmlRootElement(name="TestDoc" )
@XmlType(propOrder = { "name", "stream", "class"})
public class TestingDocument
{
	String name;
	int class;
	Subject stream;
	
	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 Subject getStream() {
		return stream;
	}
 
	@XmlElement(name = "subject")
	public void setStream(Subject stream) {
		this.stream = stream;
	}	
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<students>
    <student></student>
	<student></student>
	<student></student>
</students>

JAXB marshalling example:

package com.tst.javaxb;
 
import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
 
public class TestingDocumentExample {
	public static void main(String[] args) {
 
	  TestingDocument testDoc = new TestingDocument();
	  testDoc.setName("testuser");
	  testDoc.setAge(25);
	  Subject sub = new Subject();
	  sub.setSubject("Science");
	  sub.setSubjectType("Meth");
	  testDoc.setStream(sub);
 
	  try { 
		File file = new File("C:\\file.xml");
		JAXBContext jaxbContext = JAXBContext.newInstance(TestingDocument.class);
		Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
 
		// output pretty printed
		jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
 
		jaxbMarshaller.marshal(testDoc, file);
		//to show out put in console
		jaxbMarshaller.marshal(testDoc, System.out);
 
	      } catch (JAXBException e) {
		e.printStackTrace();
	      }
	}
}

JAXB unmarshalling example:

package com.tst.javaxb;
 
import java.io.File;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
 
public class TestingDocumentExampleUnMarshal {
	public static void main(String[] args) {
	 try {
		File file = new File("C:\\file.xml");
		JAXBContext jaxbContext = JAXBContext.newInstance(TestingDocument.class);
 
		Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
		TestingDocument tstDoc = (TestingDocument) jaxbUnmarshaller.unmarshal(file);
		System.out.println(tstDoc);
	  } catch (JAXBException e) {
		e.printStackTrace();
	  }
     }
}

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