Can Someone Help Me With Inherritance

Question

Hi I was hoping that someone might be able to help be with part of a Uni assignment I have.
One part of my assignment uses Inheritance and unfortunately I missed the lecture on this topic.
The problem goes like this:
I need to create the following 3 classes
Student class : Includes all common data from the UGStudent and GradStudent
UGStudent class : Creates a single UGStudent object. This class is descendant from Student.
GradStudent class : Creates a single GradStudent object. This class is descendant from Student.
I then have to read data in from a text file, which I can do.
Each line of the data file represents either an entry of UGStudent or GradStudent (each detail separated by ;).
The format for a UGStudent will be :
name, student id, address, contact phone number, subject number followed by list of marks (integer)
eg: Joe Bloggs;123456;1 First St, Sometown,9999;0401 234 567;9876;75;62;84
The format for a GradStudentwill be :
name, student id, address, contact phone number, previous degree, year of graduation, subject number followed by list of marks (integer)
eg: Bill Smith;111222;2 Second St, Sometown,9999;0499 876 543;B Sc;2000;5432;57;65;74
If someone could please help me on how to do this it would be greatly appreciated, or if they could point me to a solution to a similar problem for me to learn from that would be good too.
Jane

Answer 1

There are two separate issues here.
1. How to do the inheritance
2. How to create the instances
First the inheritance. You must define the three classes, where the specialized class extends the base class (Student). The base class has accessors for all the common data, and storage space for (well actually references to) the common data. The key to getting the derived classes store the common data in the base class is to use the super keyword in the derived constructor, which calls to the base class constructor.
No extra "business logic" has been included.
public abstract class Student {
    private final String name;
    protected Student(final String name, final ...) {
        this.name = name;
    public String getName() {
        return name;
public class UgStudent extends Student {
    public UgStudent(final String name, final ...) {
        super (name, ...);
public class GradStudent extends Student {
    private final String previousDegree;
    public GradStudent(final String name, ..., final String previousDegree, ...) {
        super (name, ...);
        this.previousDegree = previousDegree;
    public String getPreviousDegree() {
        return previousDegree;
}The second bit is how to create instances of the two, when reading from a file. So, you will need something as follows:
final String name = ...; // read from file
final int studentNumber = ...; // read from file
final String addresss = ...; // read from file
final String phoneNumber = ...; // read from file
final String temp = ...; // read from file.
// this will either be the first entry in the list of
// marks or it will  be the previous degree.
if (temp is a number) {
    // we are dealing with an UgStudent
    read the rest of the results and create an instance
} else {
    // we are dealing with a GradStudent
    read the year of qualification, the results and create an instance
}I have not shown how to read, nor have I shown how to determine if temp is a number. Finally, as the list of marks is probably a variable length list, I've not shown how to code this, nor capture it in the constructor. After all, some exercies must be left to the reader.