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 a different class.

I have a Course class and a Student class. Class course stores all the different courses and what I simply want to be able to do is use the name of the course, in class Student.

Here is my Course class:

public class Course extends Student
{
    // instance variables - replace the example below with your own
    private Award courseAward;
    private String courseCode;
    public String courseTitle;
    private String courseLeader;
    private int courseDuration;
    private boolean courseSandwich;

    /**
     * Constructor for objects of class Course
     */
    public Course(String code, String title, Award award, String leader, int duration, boolean sandwich)
    {
        courseCode = code;
        courseTitle = title;
        courseAward = award;
        courseLeader = leader;
        courseDuration = duration;
        courseSandwich = sandwich;

    }

}

And here is Student:

public class Student 
{
    // instance variables - replace the example below with your own
    private int studentNumber;
    private String studentName;
    private int studentPhone;
    private String studentCourse;

    /**
     * Constructor for objects of class Student
     */
    public Student(int number, String name, int phone)
    {
        studentNumber = number;
        studentName = name;
        studentPhone = phone;
        studentCourse = courseTitle;
    }

}

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

In my constructor for Student, I am trying to assign 'courseTitle' from class Course, to the variable 'studentCourse'. But I simply cannot figure how to do this!

Thank you in advance for your help, I look forward to hearing from you!

Thanks!

Solution 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);

Solution 2

I assume a Course is not a Student, so inheritance between those classes is probably a bad idea.

Solution 3

You have to declare them public.

A better way is the keep them private, and code a public getter for that variable. for example:

public Award getCourseAward(){
         return this.courseAward;
}

Solution 4

Extending Student with Couse because they are not of the same kind. Extending one class with another happens when specializing a more general (in a sense) one.
The solution would be to pass courseTitle as an argument of the Student constructor

Solution 5

It does not make sense to arbitrarily extend classes. Student is not a Course or vice versa, so you cannot extend them like that.

What you need to do is:

create a Course first:

       Course aCourse = new Course(..);

create a Student:

       Student aStudent = new Student(..);

assign the Course to the Student:

       aStudent.setCourse(aCourse.title);

View more solutions