Assignment

[Raj Kumar]

Hi, the code below doesn't give any compilation / run time errors

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class A{}
class B extends A implements E{}//line 1
class C extends A{}
class D extends B{}
interface E{}
public class Question07 {
public static void main(String[] args) {
A a = new D();//line 2
C c = new C();//line 3
E e = (E)a;//line 4
B b = (B)e;//line 5
}
}

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question :

1) How to identify that "line 4" and " line 5" is valid is it is based upon the object created / the reference it is pointing to ???

2) I need to know how the instanceof operator works for the above code for each and every condition.


Pls. let me know about these two in detail...

Thanks in advance

[Ernest Friedman-Hill]

Not sure what you're asking. The instanceof operator works at runtime. It returns "true" if the type of the object on the left is the class named on the right, any subclass of that class, or, if the right-hand argument is an interface, if that object's class, or any superclass of that class, implements that interface. Is there something specific about these cases that you don't understand?

In any event, please post SCJP questions in the SCJP forum, not here. I'll move this to SCJP for you.