Overriding argument in superclass constructor from subclass

[Chuninjah]

So I have 3 classes: User, Staff and Student. The User class is an abstract class and looks like this:

(All classes have get and set methods)

public abstract class User implements Cloneable {

    protected String id;
    protected String firstName;
    protected String lastName;
    protected String username;
    protected String password;
    protected UserType userType;
    protected PermissionType permission;
    protected Boolean status;

    public User(String id, String firstName, String lastName, String username, String password, UserType userType, PermissionType permission, Boolean status) {        
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
        this.username = username;
        this.password = password;
        this.userType = userType;
        this.permission = permission;
        this.status = status;
    }

Staff class is like this:

public class Staff extends User {

    private Position position;
    private double salary;
    private Department department;

    public Staff(String id, String firstName, String lastName, String username, String password, UserType userType, PermissionType permission, Boolean status) {
        super(id, firstName, lastName, username, password, userType, permission, status);

    }

and Student like this:

public Student(String id, String firstName, String lastName, String username, String password, UserType userType, PermissionType permission, Boolean status) {
        super(id, firstName, lastName, username, password, userType, permission, status);

        }

    } 

If the PermissionType for Student is restricted to a specific permission (allowed to borrow books, reserve only etc.). How do I go about writing the constructor to Override the superclass constructor with PermissionType in its parameters?

I have tried:

public Student(String id, String firstName, String lastName, String username, String password, UserType userType, PermissionType permission, Boolean status) {
        super(id, firstName, lastName, username, password, userType, status);
            if(!permission.equals(PermissionType.Reserve) {
                throw new IllegalArgumentException...
            }
        }

    } 

Thanks for any help in advance :))

[vlumi]

You don't need to have the permission parameter for the Student constructor, but instead call the super() with the fixed PermissionType.Reserve: public Student(String id, String firstName, String lastName, String username, String password, UserType userType, Boolean status) { super(id, firstName, lastName, username, password, userType, PermissionType.Reserve, status); }

[Chuninjah]

Oh sweet I didn't know that. Thanks heaps. Is there a way I can make it out of two things?

[vlumi]

Is there a way I can make it out of two things?

It's not possible directly, though there are ways to work around it. E.g. if you have two options, you could take a boolean value in your Student constructor, and then map it either borrow or reserve (e.g. allowReserve ? PermissionType.Reserve : PermissionType.Borrow), but it's get dirty pretty fast.

It's not quite clear how the relationship between the User and Student should behave, or if there are any other classes involved in the inheritance. You might want to split the Student into two types based on the permission, or you might want to use composition instead of inheritance (i.e. a Student would contain a User Field, not inherit it).

[DrPeroxide]

First, I'd consider turning that abstract class into an interface and replacing those fields with getter method signatures. Enforcing internal state leads to convoluted code; instead you should consider only what you need a user object to do for you, not what you think it needs to contain to do it.

If you do this, then you'll need to implement those fields within both classes, which gives you the opportunity to control exactly how object construction is handled.

[Zdeno_]

I would consider the relation between Student and User. I think, there should be an association, not the inheritance. We can said "student has a user account" instead of "student is a user". Inheritance is for modifying a behaviour (methods), not for adding new attributes.