Yikes! Why does Serialization behave like that?

[Jose Campana]

Greetings!
Here I am once again with one of my most pertinent questions, maybe this one has an obvious explanation, but I hope the motto: "There are no dumb questions" applies here as well, anyways..
If I have this:

class Zoo implements Serializable{
  private Gorila KingKong;
}
 
class Gorilla{
}

It works. But When I assign an Object to the instance variable,

class Zoo implements Serializable{
  private Gorila KingKong = new Gorilla();
}
 
class Gorilla{
}

It doesn't work.
Could someone please explain to me why this is? Shouldn't the compiler know that even though there's no Object assigned to that instance variable it belongs to a class that it's not serializable? and that can be potentially dangerous...

Thanks in advance!
sincerely,
Jose

[Ernest Friedman-Hill]

So you think the first version should not be allowed to work?

That would prevent you from implementing this:

class Zoo {
    void serializeMe(ObjectOutputStream oos) {
        KingKong = null;
        oos.writeObject(this);
    }
}

In other words, although this might be a problem, it's not always a problem, so it makes sense to allow it. Also, what if KingKong were pointing to an instance of

class BetterGorilla extends Gorilla implements Serializable {}

[Jose Campana]

Hello there !
Well, Mister Ernest, Sir... yeah, I thought it shouldn't be allowed to work, but I didn't think about polymorphism. I'm sorry, I was wrong, Now I see your point. Thank you very much for the explanation. However.......
-In the first version what would be the value of KingKong after deserialization? -- null?

Thank you for your time and detailed explanation.
Best regards,
Jose