Serialize HashMap like a Collection Property - jaxb

Question

Here I got two classes "Student" and "Course":
#XmlRootElement
class Student {
private String name;
private HashMap<String, Course> courses;
public Student() {}
public Student(String name, HashMap<String, Course> courses) {
super();
this.name = name;
this.courses = courses;
}
// -------------------------getters
#XmlAttribute(name="name")
public String getName() {
return name;
}
#XmlElement(name = "course")
public HashMap<String, Course> getCourses() {
return courses;
}
//---------------------------setters
public void setName(String name) {
this.name = name;
}
public void setCourses(HashMap<String, Course> courses) {
this.courses = courses;
}
}
#XmlRootElement
class Course {
private String id;
private String name;
public Course() {}
public Course(String id, String name) {
super();
this.id = id;
this.name = name;
}
#XmlID
#XmlAttribute(name = "id")
public String getId() {
return id;
}
#XmlAttribute(name = "name")
public String getName() {
return name;
}
public void setId(String id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
}
I want to serialize the Student class using JaxB annotations to something like the following:
<Student name="David">
<courses>
<Course id="1" name="Fundamentals of Programming"/>
<Course id="2" name="Advanced Programming">
</courses>
</Student>
Note that I want courses field of the Student to be HashMap and when unmarshalling the serialized Object use id as the key for each Course.

Answer 1

You can use an XmlAdapter for this use case. An XmlAdapter allows you to programmatically convert an object to another type for the purpose of marshalling/unmarshalling. For your use case you will convert the HashMap to an instance of an object that has a collection of Course.
http://blog.bdoughan.com/2010/07/xmladapter-jaxbs-secret-weapon.html