About Question enthuware.ocpjp.v7.2.1383 :

[tn1408]

This one could be confusing because #3 and #4 are correct.

However #1 is also correct: it will not compile because there are 2 class A

Thanks

Tony,

[admin]

No, the code is fine. You might want to try it out.

HTH,
Paul.

[tn1408]

It actually works
But why did it allow 2 classes with identical names in the same package?

Thanks,

Tony,

[admin]

Because the scope of the two classes is different. One belongs to a package, and the other one belongs to a class inside that package.

[vijayanand]

If option#3 is correct, then how B is extending A ?

Then "This program will not compile." Which implies, option#1 is correct.

[admin]

1. Why do you think option 3 has any relation to B extends A?
2. Did you try compiling the code?

[Veritas]

there are some questions (like this one) where 1 option doesn't make any sense. how would it be possible to select "none of these" if you are supposed to select 2 options?

[admin]

there are some questions (like this one) where 1 option doesn't make any sense. how would it be possible to select "none of these" if you are supposed to select 2 options?

You are right. Unfortunately, it is the side effect of having the option to hide number of correct options. When a user chooses not to display the number of correct options with each question, it makes sense.

-Paul.

[Alexey Berezkin]

The anonymous class created in main() is not final. Please try the following code:

Code: Select all

public static void main(String args[]) {
    A a = new TestClass().new A() {
        public void m() {
        }
    };
    System.out.println(Modifier.isFinal(a.getClass().getModifiers()));
}

The output is:

Code: Select all

false

[admin]

As per section 15.9.5 of JLS, anonymous class is always implicitly final.

[Alexey Berezkin]

Reported a bug to Oracle.

[sir_Anduin@yahoo.de]

@Alexey Berezkin

as i understand you are testing for a of type A. in this case a is the name, and thereby not annonymous.
You should rather (if possible) check new TestClass().new A()..... this one should return true...

[sir_Anduin@yahoo.de]

But I stil dont understand why you cant say new A() or new B()...
please give me a hint here. ("because inner class B is not static." - doesnt help)

[sir_Anduin@yahoo.de]

sorry, and another question:
am I extending the Class TestClass.A anonimously here?:

new TestClass().new A() {   public void m() { } };

[admin]

@Alexey Berezkin

as i understand you are testing for a of type A. in this case a is the name, and thereby not annonymous.
You should rather (if possible) check new TestClass().new A()..... this one should return true...

No, his code does a.getClass(), where a is pointing to an instance of the anonymous class. a is a variable name. It is not the name of the anonymous class.

[admin]

But I stil dont understand why you cant say new A() or new B()...
please give me a hint here. ("because inner class B is not static." - doesnt help)

Since class B is not a static class, it can only be created within the context of an instance of TestClass. In other words, every instance of B, has to have a reference to an instance of its outer class TestClass. If you do new A() in main, the instance of A will not be able to use "this" reference to refer to an instance of TestClass because main is static. That is why you need to do new TestClass().new A(). Java language provides this way to associate an instance of the outer class with the inner class.

HTH,
Paul.

[admin]

sorry, and another question:
am I extending the Class TestClass.A anonimously here?:

new TestClass().new A() {   public void m() { } };

Yes.

[sir_Anduin@yahoo.de]

thanks to the replies, that helped a lot
so anonymously means anonymous type, not "has no variable name"?

[admin]

thanks to the replies, that helped a lot
so anonymously means anonymous type, not "has no variable name"?

Yes, that is correct.

[krohani]

So I just want to verify something based on confusion from this question versus another question.

Inside of the main method we do not implicitly have an instance of this and therefore we need to do a new TestClass().new B().....

however if we were inside of a method inside TestClass say public void method() { } then inside of that method we could simply do a new B() without needing an explicity instantiation of TestClass with it, correct?

[admin]

Yes, you should try it out.

[jagoneye]

As per section 15.9.5 of JLS, anonymous class is always implicitly final.

Could you post the link please?

[admin]

http://lmgtfy.com/?q=section+15.9.5+of+JLS