jaxb XmlAdapter unmarshall an object from the same xml - jaxb

Question

take a look at this code :
#XmlRootElement
class Course {
private int id;
private String name;
public Course() {}
public Course(int id, String name) {
super();
this.id = id;
this.name = name;
}
#XmlAttribute(name = "id")
public int getId() {
return id;
}
#XmlAttribute(name = "name")
public String getName() {
return name;
}
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
}
class CourseAdapter extends XmlAdapter<Integer, Course>{
#Override
public Course unmarshal(Integer v) throws Exception {
// what to do hereeeeeeeeeeeeeeee????!!!!
// I want the Course with the id = v unmarshalled from
// the same xml I am unmarshalling at the moment
}
#Override
public Integer marshal(Course v) throws Exception {
return v.getId();
}
}
#XmlRootElement
class Offering {
private int id;
private Course course;
private int capacity;
public Offering() {}
public Offering(int id, Course course, int capacity) {
super();
this.id = id;
this.course = course;
this.capacity = capacity;
}
#XmlAttribute(name = "id")
public int getId() {
return id;
}
#XmlJavaTypeAdapter(CourseAdapter.class)
#XmlAttribute(name = "course")
public Course getCourse() {
return course;
}
#XmlAttribute(name = "capacity")
public int getCapacity() {
return capacity;
}
public void setId(int id) {
this.id = id;
}
public void setCourse(Course course) {
this.course = course;
}
public void setCapacity(int capacity) {
this.capacity = capacity;
}
}
#XmlRootElement
class Department {
private String name;
private ArrayList<Course> courses;
private ArrayList<Offering> offerings;
public Department(){}
public Department(String name, ArrayList<Course> courses, ArrayList<Offering> offerings) {
super();
this.name = name;
this.courses = courses;
this.offerings = offerings;
}
#XmlAttribute(name = "name")
public String getName() {
return name;
}
#XmlElement
public ArrayList<Course> getCourses() {
return courses;
}
#XmlElement
public ArrayList<Offering> getOfferings() {
return offerings;
}
public void setName(String name) {
this.name = name;
}
public void setCourses(ArrayList<Course> courses) {
this.courses = courses;
}
public void setOfferings(ArrayList<Offering> offerings) {
this.offerings = offerings;
}
}
I have marshalled my Department and this is the result:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<department name="ece">
<courses id="1" name="farsi"/>
<courses id="2" name="dini"/>
<courses id="2" name="riazi"/>
<offerings capacity="10" course="1" id="1"/>
<offerings capacity="20" course="2" id="2"/>
</department>
the problem is I do not know how to unmarshal course with the id = v from this very xml which is being unmarshalled via "unmarshal" function of CourseAdapter .

Answer 1

You can use #XmlID/#XmlIDREF for this use case without requiring an XmlAdapter.
http://blog.bdoughan.com/2010/10/jaxb-and-shared-references-xmlid-and.html