I need to "It will then call Student.addCourse with newly created Enrollment object," and I am wondering if I am doing this correctly.
this is my course reg class where i need to do this in
public Enrollment add(String RUID, String index){
 
		Enrollment r = null;
		Student s = studentRecordController.getStudent(RUID);
		Course c = courseOfferingController.getCourse(index);
		Enrollment e =  new Enrollment(s,c);
		this.student.addCourse(e);
		 this.course.addEnrollment(e);
		 return r;

heres my student class
// add an registered course to the list
		public Enrollment addCourse(Enrollment e){
 
 
			// add it to the Hashtable using its id as the key
			enrollments.put(e.getStudent(), e);
			return e;
 
		}

is this correct? It needs to add what classes this student is taking in the enrollments hash table.
Also question instead of having addCourse(Enrollment e) could i have addCourse(String RUID string index)? Our professor gave us the structure but idk why he has it enrollment e. There is a class called Enrollment but i dont see why we need it.
here is the enrollment class 
public class Enrollment {
	Student student;
	Course course;
	String grade;
 
 
	public Enrollment (Student studentS, Course courseC ){
		student = studentS;
		course = courseC;
 
	}
	public void setCourse(Course course) {
		this.course = course;
	}
	public Course getCourse() {
		return course;
	}
 
	public void setGrade(String grade) {
		this.grade = grade;
	}
	public String getGrade() {
		// when assign a grade to a student
		// you also need to recalculate GPA
 
		return grade;
	}
 
	public void setStudent(Student student) {
		this.student = student;
	}
	public Student getStudent() {
		return student;
	}
 
}