Java Abstract Class And Generics

Question

I'm trying to modify a class AuthenticatedUser to store a list of AdminRole's. AuthenticatedUser is a class used by all my applications; it gets put into a session when the user logs in successfully. Now I want to add a list of authorization roles to the user session. However each application defines the an AdminRole class a little differently. For example, my DataCenter application stores in the database:

  employee_id
  role_name
  site_name
  receive_email

Not all of my applications will need the receive_email field or may want to extend their own methods. I figured this called for an abstract class. But Eclipse is complaining about the wrong Type on the Authorized_role_list setter here in this snippet.

  DataCenterAdminRoleDAO dcAdminDao = new DataCenterAdminRoleDAO();
  try {
      List<DataCenterAdminRole> authorized_roles = dcAdminDao.getAuthorizedRoleListByBadge(authenticatedUser.getBadge());
      authenticatedUser.setAuthorized_role_list(authorized_roles);

=== Classes

public class AuthenticatedUser extends Employee implements Serializable {   
  private static final long serialVersionUID = 1L;
  private List<AdminRole> authorized_role_list;
  ...
}

public abstract class AdminRole implements Serializable {
  private static final long serialVersionUID = 1L;
  private String role_name; //regular, admin, editor, etc..
  private String site_id;  //company branches
  ...
}

public class DataCenterAdminRole extends AdminRole implements Serializable {

Obviously a fix is to return a list of AdminRole in my Datacenter implemetation but I thought by extending the abstract class I could pass the subclass. What am I missing?

Answer 1

If it's the setter that is giving you trouble you can use a lower bound with a wildcard on the authorized_roles_list

private List<? extends AdminRole> authorized_role_list;
....
public setAuthorized_role_list(List<? extends AdminRole> authorized_roles) {
...
}