Polymorphism

[jibs parap]

In K&B's book, under the polymorphism topic, it says :
'at runtime, the ONLY things that are dynamically selected based on the actual object (rather than the reference type) are instance methods. Not variables'

I think and prove that instance variables are also dynamically selected.

Am I right?

[Shaan Shar]

Originally posted by j . thexyz:
In K&B's book, under the polymorphism topic, it says :
'at runtime, the ONLY things that are dynamically selected based on the actual object (rather than the reference type) are instance methods. Not variables'

I think and prove that instance variables are also dynamically selected.

Am I right?

Hi J.

Are you asking about anything then it would be great if you would have been give some example.

So if you are going to prove something then , Please let all of us know what you want to prove and how???

[Deepak Bala]

Why dont you give us your example and we ll tell you. Also... please change your name to fit java ranch naming policy

[David O'Meara]

"j thexyz",

We're a friendly group, but we do require members to have valid display names.

Display names must be two words: your first name, a space, then your last name. Fictitious names are not allowed.

Please pay attention and select a valid diaplay name or your account will be closed.

thanks,
Dave

[jibs parap]

All I mean is, if the subclass has declared an instance variable with the same name as that in superclass, the subclass variable is dynamically invoked.

For eg:
class GameShape {
int i = 10;
// more code
}

class PlayerPiece extends GameShape {
int i = 20;
// more code
}

}

public class Test1{
public static void main (String[] args) {
PlayerPiece shape = new PlayerPiece();
System.out.println("i= "+shape.i);
// more code
}
}

OUPUT IS 'i= 20'

Am I thinking in the right direction?

[Leonardo Luiz]

Hi,

Your example has a mistake. The compiler selects i=20 based on shape type, PlayerPiece.

It's on compile time, not dynamically.

In my example you can see it more clearly


class A {
public int v = 1;
}

public class B extends A {
public int v = 2;

public static void main(String args[]){
A obj1 = new A();
A obj2 = new B();

System.out.println(obj1.v + " - " + obj2.v);
}
}

The output is:
1 - 1

[jibs parap]

Thanks v much.