Enthuware

I understand fi in A is final but the object reference by b is still B. Why is a cast of the object B referring to A's field?

Access to variables depends on the class of the reference (and not on the class of the object). Casting a reference effectively changes the class of the reference used to access the variable. You need to read about variable hiding or shadowing. This link should help: http://blog.sanaulla.info/2008/06/27/sh ... mystified/

HTH,
Paul.

Hello,

Was shadowing possible if the class B doesnt extend A ?

Thanks ,
Srijith

Shadowing can also happen when you have an instance member and a local method variable with the same name. Within the method, the local variable shadows the instance member. You may read more about it here: http://docs.oracle.com/javase/specs/jls ... ml#jls-6.4

what would be the output if it was like:

System.out.println( ( (A) new B() ).fi );

What did you get when you tried it out?

it printed 10, why?

I thought it would print 15 since i'm just using a new object of B.

Access to all variables (and to all static methods) always depends on the type of the variable and not on the type of the object. This is a fundamental concept in polymorphism. I would suggest you to go through a good book to learn the basics before attempting mock exams.

vchhang wrote: ↑

Thu Jun 05, 2014 9:15 am

I understand fi in A is final but the object reference by b is still B. Why is a cast of the object B referring to A's field?

example without casting:
A b1 = new B();
System.out.println(b1.fi );//print 10

I have not yet understood what makes the "final" keyword for a difference in this question.
When I delete "final" it have the same result

PS
final in class B is clear

It makes no difference. It is there just to confuse the candidate because final, when applied to a method, produces a different behavior.