When a class extends from an abstract class then how to access its private variables?

Question

I have an abstract class A and class B extends from it.I made those variables private and its fine.

public abstract class A  {
    private String name;
    private String location;

public A(String name,String location) {
        this.name = name;
        this.location = location;
}
 public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }


    public String getLocation() {
        return location;
    }

Then I want to write the class B.

public class B extends A{
private int fee;
private int goals;   // something unique to class B

I don't understand how to write a constructor for class B to access it's private variables. I wrote something like this and its wrong.

    B(int fee, int goals){
       this.fee= fee;
       this.goals=goals;
     }

Can u help me to solve this with a short explanation.

its not wrong, the problem because you need to construct your parent class first before you can construct your B class, so you need to call super(name, location) on B constructor to construct the parent first. — Wajdy Essam, Nov 15 '14 at 15:01
[As there is no default (or no-arg) constructor in the parent abstract class the constructor used in subclasses must be specified.](http://stackoverflow.com/a/260755/2830834) — Sagar Pudi, Nov 15 '14 at 15:09
Thanks Friends for the help :) now i understood it very well — , Nov 15 '14 at 15:22

score 5 · Accepted Answer · answered Nov 15 '14 at 15:00

The above should be fine, except that you have to specify a call to A's constructor, since by constructing a B, you're also constructing an A

e.g

public B(int fee, int goals) {
    super(someName, someLocation); // this is calling A's constructor
    this.fee= fee;
    this.goals=goals;
}

In the above you somehow have to determine how to construct an A. What values will you specify for A ? You would normally pass that into the constructor for B e.g.

public B(int fee, int goals, String name, String location) {
    super(name, location);
    this.fee= fee;
    this.goals=goals;
}

thanks Brian now i understood it and now it works fine.Thankyou very much — , Nov 15 '14 at 15:19

Anthony Raymond · Answer 2 · 2014-11-15T15:09:52.897

1

You do not have a default constructor for class A. It means you must specifies a call to A constructor from B constructor.

public B(String name, String location int fee, int goals) {
    super(name, location); // this line call the superclass constructor
    this.fee = fee;
    this.goals = goals;
}

If a class inherit another, when you construct the child Class an implicit call to the mother class constructor is also done. Since your A does not have default constructor, it means you want to use a specific one, so you must call it explicitly.

edited Nov 15 '14 at 15:09

answered Nov 15 '14 at 15:03

Anthony Raymond

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Thank you very much Anthony now i got it. – Nov 15 '14 at 15:20

When a class extends from an abstract class then how to access its private variables?

2 Answers2