How to use a variable of one class, in another in Java?

Question

I\'m just working through a few things as practice for an exam I have coming up, but one thing I cannot get my head round, is using a variable that belongs to one class, in

Answer 1

Am I correct in using 'extends' within Course? Or is this unnecessary?

Unfortunately not, if you want to know whether your inheritance is correct or not, replace extends with is-a. A course is a student? The answer is no. Which means your Course should not extend Student

A student can attend a Course, hence the Student class can have a member variable of type Course. You can define a list of courses if your model specifies that (a student can attend several courses).

Here is a sample code:

public class Student{
    //....
    private Course course;
    //...
    public void attendCourse(Course course){
       this.course = course;
    }
    public Course getCourse(){
       return course;
    }
}

Now, you can have the following:

Student bob = new Student(...);
Course course = new Course(...);
bob.attendCourse(course);