Casting a child class into a parent class.

[Unsub]

Hi there, new to the forums and plan on staying for a very very long time. :o

My question, as the title states:

-Is it possible to cast an object of a child class into an object of its parent class and if so, how is it coded?

This is what I've been tinkering with thus far..

Example:

ChildClass a = new ChildClass();
ParentClass b = (ChildClass)a;



-Unsub

[r035198x]

The ChildClass object is already a ParentClass object so there is no need to cast.
Putting the cast is just redundant.

[Unsub]

The ChildClass object is already a ParentClass object so there is no need to cast.
Putting the cast is just redundant.

Got it.

What about the other way around, could I cast a parent class into a child class?

-please forgive me if these seem like noobish questions. I've just entered the world of programming and am just starting to dive in to it all.

[r035198x]

You can. The compiler won't complain. You could get a runtime exception though if the object cannot be cast to that type at runtime.

[rummy]

Here by i give the casting procedures and problems,related to inheritance


superclass=subclass (This is valid)


subclass=(subclass)superclass (This is valid at compile time but shows an error in run time-ClassCastException)


subclass=superclass (Shows error in compile time itself)

[Tolls]

subclass=(subclass)superclass (This is valid at compile time but shows an error in run time-ClassCastException)

No it doesn't...see:

Superclass superc = new Subclass();
Subclass subc = (Subclass) superc;

is perfectly valid at runtime.

[Unsub]

I think I understand now. Thanks everyone.

[helpisontheway]

I think it's called polymorphism.

If you extend it, you can use the superclass type & connect it to the subclass.