Classes scheduler problem

public class Scheduler {
    static Random rand = new Random();

    public static void main(String args[]) {
        List<Slot> slots = new ArrayList<Slot>(); // Create timeslot List
        Slot slotm1 = new Slot("M1"); // Create timeslot (parameter: identifier = M/T/W/H/F for day of week, hour number)
        Slot slotm2 = new Slot("M2"); // Create timeslot
        // More slots
        slots.addAll(Arrays.asList(slotm1,slotm2)); // Add slots to List

        List<Course> courses = new ArrayList<Course>(); // Create courses List
        Course biologyI = new Course("biology I",2,slots); // Create course (parameters: name, number of slots per week, slots List)
        Course chemistryI = new Course("chemistry I",2,slots); // Create course
        Course civsocI = new Course("civics & society I",2,slots); // Create course
        // More courses

        courses.addAll(Arrays.asList(biologyI,chemistryI,civsocI); // Actually

        List<Student> students = new ArrayList<Student>(); // Create students List
        List<Course> studentCourses = new ArrayList<Course>(); // Create temporary storage for student courses

        studentCourses.addAll(Arrays.asList(biologyI,civsocI)); // Add courses relevant to student
        Student nicolaos = new Student("Nicolaos Haakonsson",studentCourses,slots,0); // Create student

        studentCourses.clear(); // Clear temporary storage for student courses
        studentCourses.addAll(Arrays.asList(biologyI,chemistryI)); // Add courses relevant to student
        Student hide = new Student("Hide Tosell",studentCourses,slots,1); // Create student

        // More students

        students.addAll(Arrays.asList(nicolaos,hide)); // Add students to list

        Student randStudent = students.get(rand.nextInt(students.size()));
        System.out.println("The following courses have been found for student " + randStudent.getName() + ": ");
        for(int i=0; i<randStudent.getCourses().size(); i++) { // Cycle through all courses stored in student's courses List
            System.out.print(randStudent.getCourses().get(i).getName()); // Get name of course i
            if(i < randStudent.getCourses().size()-1) System.out.print(", "); // For readability
        }
    }
}

public class Course {
    private Random rand = new Random();
    private List<Student> students = new ArrayList<Student>(); // List storing students attending this course (unused in segment)
    List<Slot> slots = new ArrayList<Slot>(); // List containing all possible timeslots

    private String name;
    private int points;

    // Constructor
    public Course(String name, int points, List<Slot> slots) {
        this.name = name;
        this.points = points;
        this.slots = slots;
    }

    public String getName() {
        return name;
    }
}

public class Student {
    private String name;
    private List<Course> courses = new ArrayList<Course>(); // List storing courses attended by this student
    List<Slot> freeslots = new ArrayList<Slot>(); // List storing slots still available (unscheduled) for student (unused in segment)
    private int studentnr; // Student identifier

    // Constructor
    public Student(String name, List<Course> courses, List<Slot> slots, int studentnr) {
        this.name = name;
        this.freeslots = slots;
        this.courses = courses;
        this.studentnr = studentnr;
    }

    // courses getter
    public List<Course> getCourses() {
        return courses;
    }

    // name getter
    public String getName() {
        return name;
    }
}


/*
* Output given:
*
* The following courses have been found for student Nicolaos Haakonsson:
* biology I, chemistry I
*/