About Question enthuware.ocpjp.v17.2.3721 :

[Val Martinez]

As for me, the first option marked as wrong,

Code: Select all

if (a instanceof A a1) a1.a();

does work perfectly in a real enviroment with JDK17

[admin]

No, it doesn't. Please make sure you have copied the code correctly.

[Badem48]

I do not know if it is just me but this code, which is first option works on my machine?

Code: Select all

public class TestClass {
    public static void main(String[] args) {
        B b = new C();
        A a = b;
        if (a instanceof A a1) a1.a();

    }
}

class A {
    void a(){ System.out.println("a"); }
}
class B extends A {
    void b(){ System.out.println("b"); }
}
class C extends B {
    void c(){ System.out.println("c"); }
}

[admin]

It doesn't compile on Java 17 but compiles on Java 21.
This is due to a change in the Java language specification for instanceof.

[likejudo]

It doesn't compile on Java 17 but compiles on Java 21.
This is due to a change in the Java language specification for instanceof.

Then why is the question on the exam?

[admin]

Not sure what is your question. Do you mean why this question is there in our mock exams? It is because this topic is on the OCP 17 exam. The answer and the explanation provided in the s/w are as per Java 17.

[likejudo]

Not sure what is your question. Do you mean why this question is there in our mock exams? It is because this topic is on the real OCP 17 exam. The answer and the explanation are as per Java 17.

Thanks. You mentioned that it does not compile on 17, but on 21. If I understood your comment above.

[admin]

That was in response to another user. It worked on their system most likely because they were using Java 21. It works on Java 21 because of the reason mentioned above. But the exam is for Java 17, so option 1 is incorrect.