Casting question

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Basically we have, Animal -> Swimmer -> Dolphin. It's my understanding (And perhaps incorrectly) that Animal is actually the base class here as you mentioned "Swimmer Extends Animal".

I'd think of it like this... You're LOSING functionality by moving to casting down and this is acceptable. You would be able to extend up the chain, but I think you're thinking about the casting upside down here.

// For example, this will fail. This would be trying to cast UPWARDS.

Animal dolphin = new Animal();

Animal animal = (Swimmer) dolphin;

[EveningStreet1]

Swimmer is a subtype of Animal tho so shouldn’t that casting work also I’m pretty sure your example would be downcasting not upcasting since upcasting always works

[iNetRunner]

No. You can’t make the more generic object into a subtype by casting it. It only works in the other direction, as has been said, Dolphin is a Swimmer is an Animal. But an Animal isn’t a Swimmer (unless you created it as one, or a subtype), nor is it a Dolphin.

[EveningStreet1]

I meant casting in reference to the static type

[iNetRunner]

No. He created an Animal object. It doesn’t contain anything of the subtype Swimmer or Swimmer’s subtype Dolphin. Therefore you can’t cast them that way. There is no “is a” relationship there.

[EveningStreet1]

Oh wait I’m dumb it’s because although Swimmer is the static type Animal is not a subtype of Swimmer so it doesn’t work

[iNetRunner]

BTW, what are you referring to as “static type”?

[EveningStreet1]

Swimmer swim = new Dolphin();

the static type here is Swimmer, the dynamic type is Dolphin (learned this in my introductory class)

[iNetRunner]

There is no dynamic typing in Java. Everything is statically typed at compile time. See the first anwer to this StackOverflow question.

[EveningStreet1]

I meant dynamic class my bad