when does JAXB unmarshaller.unmarshal returns a JAXBElement or a MySchemaObject?

If the root element uniquely corresponds to a Java class then an instance of that class will be returned, and if not a JAXBElement will be returned.

If you want to ensure that you always get an instance of the domain object you can leverage the JAXBInstrospector. Below is an example.

Demo

package forum10243679;

import java.io.StringReader;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;

public class Demo {

    private static final String XML = "<root/>";

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Root.class);
        Unmarshaller unmarshaller = jc.createUnmarshaller();
        JAXBIntrospector jaxbIntrospector = jc.createJAXBIntrospector();

        Object object = unmarshaller.unmarshal(new StringReader(XML));
        System.out.println(object.getClass());
        System.out.println(jaxbIntrospector.getValue(object).getClass());

        Object jaxbElement = unmarshaller.unmarshal(new StreamSource(new StringReader(XML)), Root.class);
        System.out.println(jaxbElement.getClass());
        System.out.println(jaxbIntrospector.getValue(jaxbElement).getClass());
    }

}

Output

class forum10243679.Root
class forum10243679.Root
class javax.xml.bind.JAXBElement
class forum10243679.Root