Procedural confusion (several questions)

Question

My task is to develop a Course Management System:
I have the desired variables for an abstract Course class which will be extended by 3 subclasses of CourseType
Side: this task is due in 6 days and the how and why are becoming blurred
At this time I don't have working code (when I run it I get no result) so I'm back to starting over
Q1 I want my subclasses to inherit my super variables but I understand that if I define 'private' variables they are not inherited .... which is 'proper coding'?
Declare the variables as public (available anywhere) or declare protected (there is no need for them to be accessed from outside the project).
appropriate security levels are one of the criteria of the task (and I've confused myself)
Q2 Methods will be inherited by subclasses, with mutator methods which provide subclass specific data being overwritten accordingly. Would I be correct in assuming the 'How' for this section will depend on my chosen option above?
Q3 In java 1.6; which is the preferred variable Array method .... Vector() or ArrayList() ?

Answer 1

Thanks Keith
This assignment is actually part 2, I missed the first part because my motherboard died (and the tutor hasn't posted the solution yet)
so I'm sort of working blind
Part 3 is to create the GUI App, so I'm trying to code with that in mind
in part 1, it was suggested that we use a Courses interface which would be implemented by the Course class (which is in turn, extended by CourseType classes; I don't understand interfaces so I've opted for an abstract Course class because I can't define methods in an instance.
I have the abstract Course class, a Student class, and I've tried to put together a working Course.CookingCourse subclass
package <packageName>;
import java.util.*;
public abstract class Course
    private int ID = 0;
    private String courseTitle;
    private String teacher;
    private int MAX_STUDENTS;
    private ArrayList listStudents = new ArrayList();
    private int totalStudents = listStudents.size();
    private double standardCharge;
    private double income;
    private double runCost;
     * A Scanner instance, for reading data inputs from the keyboard
    private static Scanner console = new Scanner(System.in);
    private String inputLine = console.nextLine();
    private String inputString = console.next();
    public int getID()
        return ID;
    public int newID()
        getID();
        ID = ID + 1;
        return ID;
    public String setCourseTitle()
        System.out.println("What is the Title of this Course?");
        courseTitle = inputLine;
        return courseTitle;
    public String getCourseTitle()
        return courseTitle;
    public String getTeacher()
        return teacher;
    public String assignTeacher()
        /** check if we have assigned a teacher yet */
        if (getTeacher().length() < 1)
            /** If there is no teacher, assign one */
            System.out.println("Who will teach this Course?");
            while (console.hasNext())
                String firstName = inputString;
                String lastName = inputString;
                teacher = firstName + " " + lastName;
        } else
            /** there is a teacher assigned */
        return teacher;
    public int setMAX_STUDENTS(int val)
        this.MAX_STUDENTS = val;
        return MAX_STUDENTS;
    public int getMAX_STUDENTS()
        return MAX_STUDENTS;
    public int getTotalStudents()
        return totalStudents;
    public double setStandardCharge(double charge) {
        this.standardCharge = charge;
        return standardCharge;
   public double getStandardCharge()
        return standardCharge;
    public double getIncome()
        return income;
    public double getRunCost()
        return runCost;
     * Calculates the running cost for the course, based on the formula
     * provided. The formula is entered per instance.
     * @return runCost
    public abstract double calculateRunCost();
}Do I need to define a constructor for an abstract class?
package <packageName>;
import java.util.*;
public class CookingCourse extends Course
    int ID = super.getID();
    String courseTitle = super.setCourseTitle();
    String teacher = super.assignTeacher();
    final static int MAX_STUDENTS = super.setMAX_STUDENTS(10);
    ArrayList listStudents;   
    int totalStudents = super.setTotalStudents();
    double standardCharge;
    double income;
    double runCost;
    /** Default constructor */
    public CookingCourse()
        this.ID = super.newID();
        this.courseTitle = super.setCourseTitle();
        this.teacher = super.assignTeacher();
        this.MAX_STUDENTS = super.setMAX_STUDENTS(10);
        this.listStudents = new ArrayList();
        this.totalStudents = listStudents.size();
        this.standardCharge = setStandardCharge();
        this.income = 0.0;
        this.runCost = calculateRunCost();
     * Custom constructor with declared variable
     * @param courseTitle
    public CookingCourse(String courseTitle) {
        this.ID = super.newID();
        this.courseTitle = courseTitle;
        this.teacher = super.assignTeacher();
        this.MAX_STUDENTS = super.setMAX_STUDENTS(10);
        this.listStudents = new ArrayList();
        this.totalStudents = listStudents.size();
        this.standardCharge = setStandardCharge();
        this.income = 0.0;
        this.runCost = calculateRunCost();
     * Stores the standard charge for the course
     * @return standardCharge
    public double setStandardCharge() {
        double charge;
        if(courseTitle == "Italian Cooking"){
             charge = 500.0;
        } else { // courseTitle == "Seafood"
            charge = 700.0;
        this.standardCharge = charge;
        return standardCharge;
     * Calculates the cost of running the course according to the
     * formula provided
     * @return runCost
    @Override
    public double calculateRunCost()
        double formulaBase = 1000.0;
        double formulaVarient = totalStudents * 50.0;
        runCost = formulaBase + formulaVarient;
        return runCost;
}And, the Student class
package <packageName>;
import java.util.Scanner;
public class Student
    private String name;
    boolean fifty = false;
    boolean returning = false;
    private String address;
    private int age;
    private double courseFees = 0.0;
     * create a Scanner for reading data inputs from the keyboard
    private static Scanner console = new Scanner(System.in);
    private String inputLine = console.nextLine();
    private int inputInt = console.nextInt();
     * Student Constructor
     * Since each name will be unique, we create the student instance
     * by directly entering this information
     * @param name
    Student(String name)
        this.name = name;
        this.fifty = false;
        this.returning = false;
        this.address = setStudentAddress();
        this.age = setAge();
        this.courseFees = 0.0;
    public String setStudentAddress()
        System.out.println("Enter the Student's address: ");
        System.out.println("Hit <Enter> if not supplied");
        if (inputLine.length() == 0)
            address = "Address Unknown";
        } else
            address = inputLine;
        return address;
     * Calculates the Student's age by obtaining their Date of Birth and
     * comparing it to today's date.
     * By utilising this method, we can dynamically calculate the age of
     * returning students.
     * @return age
    public int setAge()
        // Get today's date, so we can calculate age
        long today = new java.util.GregorianCalendar().getTime().getTime();
        System.out.println("Enter the Student's Date of Birth: (dd mm yyyy)");
        int day = inputInt;
        int month = (inputInt - 1);
        int year = inputInt;
        long birthDate = new java.util.GregorianCalendar(year, month, day)
                .getTime().getTime();
        long diff = today - birthDate;
        // Convert milliseconds back to years
        long y_diff = diff / 1000 / 60 / 60 / 24 / 365;
        age = (int) y_diff;
        if (age > 49)
            fifty = true;
        return age;
    public double setCourseFees()
        // TODO
        return courseFees;
    public String getStudentName()
        return name;
    public String getStudentAddress()
        return address;
    public int getAge()
        return age;
    public double getCourseFees()
        return courseFees;
     * Add a new student
    public void addStudent()
        new Student(name);
}I have yet to create the StudentRegister class, which will be our expanding array list of all students registered regardless of enrolment status.
The ArrayLists within each Course will only contain students for that course (but I'm still unclear on the 'How' .... will consult textbook for that though)
Edited by: kcstingel on 21/04/2008 22:05