Need help on Casting in objects

[Anantha Krishna]

Hi all,
I am not able to understand the casting procedures with respect to objects.
I have one top level class called citrus which implements sqeezable interface. And 3 subclasses lemon tangelo & grapefruit
In the following code
grapefruit g,g1;
citrus c;
tangelo t;
g=new grapefruit();
c=g;
g1=(grapefruit)c;//legal (1)
t=(tangelo)c//illegal. (2)
Its' confusing why statment 1 is legal and 2 is illegal(This is given in R& H).
Please help me out.
Thanks & regards
Ananth

[bill bozeman]

It is because when you initialized c, you set it to a grapefruit, with that statement c = g; Since c is really a grapefruit, you can cast it back down to a grapefruit object g1. But since c was never a tengelo, you can't cast it back down to something it never was.

[Anantha Krishna]

Hi Bill,
One more clarification. Is it possible to again reassign c to t
like this.
Tangelo t1
c=t;
and then do
t1=(tangelo)c
Thanks and regards
Ananth

[bill bozeman]

Try it out and tell me what you get.

[Anantha Krishna]

Hi,
It's working.
Thank you bill
Ananth