Casting a child class into a parent class.

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

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

Quote:

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Originally Posted by r035198x

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

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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.

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.

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)

Quote:

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

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No it doesn't...see:

Code:

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

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is perfectly valid at runtime.

I think I understand now. Thanks everyone.

I think it's called polymorphism.

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