jaxbSubstitution

<xs:complexType name="department">
 <xs:complexContent>
  <xs:extension base="subunit">
   <xs:sequence>
    <xs:element ref="name"/>
    <xs:element name="manager" type="employee"/>
    <xs:element ref="subunit" maxOccurs="unbounded" minOccurs="0"/>
   </xs:sequence>
  </xs:extension>
 </xs:complexcontent>
</xs:complextype>

    public static Company deserializeCompany(File input)
    throws JAXBException 
    {
        initializeJaxbContext();
        Unmarshaller unMarshaller = jaxbContext.createUnmarshaller();
        return (Company) unMarshaller.unmarshal(input);
    }

    public static void serializeCompany(File output, Company c)
    throws     JAXBException,
            FileNotFoundException,
            XMLStreamException 
    {
        initializeJaxbContext();
        OutputStream os = new FileOutputStream(output);
        Marshaller marshaller = jaxbContext.createMarshaller();
        XMLOutputFactory outputFactory = XMLOutputFactory.newInstance();
        XMLStreamWriter writer = outputFactory.createXMLStreamWriter(os);
        marshaller.marshal(c, writer); // TODO: need a stream writer that does indentation
    }

public class Total {

	public static double total(Company c) {
		double total = 0;
		for (Department d : c.getDepartment())
			total += total(d);
		return total;
	}

	public static double total(Department d) {
		double total = total(d.getManager());
		for (JAXBElement<? extends Subunit> s : d.getSubunit())
			total += total(s.getValue());
		return total;
	}

	public static double total(Employee e) {
		return e.getSalary();
	}

	//
	// We cannot use virtual methods.
	// That is, we do not allow ourselves modifying schema-derived classes.
	//
	public static double total(Subunit s) {
		if (s instanceof Department)
			return total(((Department)s));
		else if (s instanceof Employee)
			return total(((Employee)s));
		else throw new IllegalArgumentException();
	}

}

public class Cut {

    public static void cut(Company c) {
        for (Department d : c.getDepartment())
            cut(d);
    }

    public static void cut(Department d) {
        cut(d.getManager());
        for (JAXBElement<? extends Subunit> s : d.getSubunit())
            cut(s.getValue());
    }

    public static void cut(Employee e) {
        e.setSalary(e.getSalary() / 2);
    }

    public static void cut(Subunit s) {
        if (s instanceof Department)
            cut(((Department)s));
        else if (s instanceof Employee)
            cut(((Employee)s));
        else throw new IllegalArgumentException();
    }

}