Getting a subclass element from the abstract superclass type list

findUser.java

private List<Manager> _managers = new ArrayList<Manager>();
private List<Employee> _employees = new ArrayList<Employee>();
private List<User> _usrs = new ArrayList<User>();

public User findUser(String userID){
		
	refreshUserList(); //updates _usrs so it has all the current users
	Iterator<User> i;
	User u = null;  //abstract class User
	i = this._usrs.iterator();   
		
	while(i.hasNext()) {
		u = i.next();
		if(u.getID().equals(userID)){
			if(u.getRole().equals("employee")) {
				u = (Employee) u;  //Employee extends User
				break;
			}
			u = (Manager) u;  //Manager extends User
		}
	}
	return u;
}