About Question enthuware.ocajp.i.v7.2.1136 :

[ETS User]

I coded this example up and tested it out...

Code: Select all

System.out.println(b instanceof A);

prints "true"...

though this was marked as an incorrect answer.

Please advise.

-- Robert

[admin]

The option says, "(b instanceof A) will return false". That is why it is the wrong option.

HTH,
Paul.

[Kipchakbaev]

Code: Select all

class TestClass{    
     public static void main(String[] args){       
          A a = new A();       
          B b = new B();    
     }; 
} 
class A implements T1, T2{} 
class B extends A implements T1{} 
interface T1 { } 
interface T2 { }

How is it possible that

(b instanceof T2) will return true.

is a correct statement?

[admin]

Did you try it out?

It is true because b extends A and A implements T2.

HTH,
Paul.

[Kipchakbaev]

Well, I just ran it, and (b instanceof T2) returned true
I studied hard, but this question caught me.

Thank you Paul!
Enthuware is really useful.

[AndaRO]

It's about to be transitive.
If b instanceof A return true and a instanceof T2 return true means that b instanceof T2 return true?

Please say me if I am correct.

[admin]

Please post complete code so that it is clear what you are asking. Also, please post what was the result of compilation and execution of your code.