About Question enthuware.ocajp.i.v7.2.1220 :

[ETS User]

I tried executing this program so just wanted to make sure whether class A and B are in the class file C. If all of them are in the same class file then i think option1 will work.

Please advise!

[Guest]

I am sorry the answer was correct... i wrote program wrongly.

[fasty23]

Is it Not possible if the variable of class A is private so b.i refers to variable of class B?

[admin]

No, explanation to option 1 explains it.

[trovanfloyd]

The answer that question is wrong. I'm sure that option 3 - System.out.println(b.i); will print 20 - is correct. I've tested that situation and I saw that "b.i" works perfectly

[admin]

The answer that question is wrong. I'm sure that option 3 - System.out.println(b.i); will print 20 - is correct. I've tested that situation and I saw that "b.i" works perfectly

Please try the code that is given in the question exactly as given.

HTH,
Paul.

[subhamsdalmia]

Compiler says cannot make a static reference to a non-static field.

class A{
private int i = 10;
public void f(){}
public void g(){}
}

class B extends A{
public int i = 20;
public void g(){}
}

public class C{
A a = new A();//1
A b = new B();//2
public static void main(String[] args) {
System.out.println(b.i);
}
}

Also, how will we be able to access "i" in class B?

[admin]

The code that you are trying to compiler is probably different from what you've pasted here.

[subhamsdalmia]

Sir,
I have pasted the program as is,
My question is that since "i" is public in class B, how can we access it?

[admin]

Sir,
I have pasted the program as is,
My question is that since "i" is public in class B, how can we access it?

Variables and static methods are not overridden and so access to variables and static methods is determined at compile time based on the type of the variable (instead of type of the object referred to by the variable, as is the case with instance methods.)
So if you declare b to be of type B, you can access b.i.

[Javier]

Hi!

I would like to know why is compiling and running without problem the statement:

b.f();// A has got f(), but the object is of type B.
If there is not method f() in the B class...

Why is running without problem??

Thank you!!

[admin]

If B is a subclass of A and if A has non private f() then B will inherit f(). Thus, there is no issue in calling b.f().

[smahale]

In the given code,

public class C{
A a = new A();//1
A b = new B();//2
}

if we were to do System.out.println(a.i);
Would this now print 10, or would it be a compile error?

Thanks!

[admin]

What happened when you tried it out?

[burlacu.valeri]

Hi,

public void f(){}

why b.f( ) is compile error?

For me, it works without errors ... :/

[admin]

Hi,

public void f(){}

why b.f( ) is compile error?

For me, it works without errors ... :/

It is not a compile error that is why this option is not correct. Option 5, "None of the above statements is correct", is the correct option.

[burlacu.valeri]

Hi,

ok, now I have understood.