Quiz Time

[sukatoa]

Im back!!!!

@ rjuyal, you have the correct guess,

@ eku, lacking....

actually it is compilable and runnable code....
There is a member here who asked about nested extending of abstract classes(i may be wrong of its term)... i doubt at first, bec i really don't use that kind of implementation, and i replied to him that experimental code.....

@ eranga,
all within the contructor test will first to execute before at the main method... you're right....

@Jesdisciple
you're correct too,

Quote:

But I think the compiler would complain that "Class B cannot be found" or something to that effect.

the compiler will not complain....

Generally, any class that was extend at the main class(handler) can be invoked its method within the main class by "this" referencing....
Any abstract classes that was extended from other abstract class which extended also in the main class(handler), can be invoked its method directly to main class(handler)...

next quiz please?!!

[Eranga]

But I think you should have compiler warning. Because you are accessing non-public types here, through a public. Isn't it?

[sukatoa]

no warnings at all....

because, if the said abstract classes were not specified as public or private, it will then set to the default(can access within the package)....

and obviously the abstract classes are together with the main class(test)

please correct me if i'm wrong,

you can test the code with -Xlint

[Eranga]

Ok, I'm talking about this.

Code:

public class test extends B

Class B is not a public class, so you are exporting a non-public class here in a public class. Best thing to do is, define the test class with default modifiers. It's a fixable warning, generally we called it is.

It's better check this myself too on an IDE now.

[sukatoa]

What's the result?!!

[Eku]

@sukatoa. . . I was really confused on that question. ^_^ another lesson learned

[Eranga]

Quote:

Originally Posted by sukatoa

What's the result?!!

Nothing, there is a warning. But your code is still compiled and run perfectly. All about access modifiers level.

[Jesdisciple]

What's the result (output or compile/runtime error/exception) of this?

Code:

class B {
    String value;
    B(String value){
        this.value = value;
    }
    public String toString(){
        return value;
    }
    static void test(A<? extends Object> a){
        a.set(new B("foo"));
        System.out.println(a.get());
    }
    public static void main(String[] args){
        A<B> a = new A<B>();
        test(a);
    }
}
class A<T> {
    private T o;
    void set(T o){
        this.o = o;
    }
    T get(){
        return o;
    }
}

[Eranga]

This is much simpler pal. Got the compile error.

It's all about set()

[Jesdisciple]

Did you compile it, then?

[Eranga]

Oh, I'm not compile it. It wont compile it, because set() on class A not extended, but in class B you tried it. So it wont compile.

Simply incompatible method signature found.

[rjuyal]

1st thing first

Quote:

Class B should be declared as public to run this program

[Eranga]

I think still you get the same warning.

[rjuyal]

why i don't get the notification

anyways which kinda warning?

[Eranga]

Should be much similar to this.

Quote:

set(extends object) in class A<extends object> cannot be applied to class B

I guess it should be. Why is that your Eclipse doesn't give such notifications.

I'm not sure my NetBeans give it too.

[rjuyal]

Quote:

Why is that your Eclipse doesn't give such notifications

My Eclipse will certainly give much more elaborated, correct, acceptable ( out of words, add from your side ) warning. but i have not compiled it though,as the rule says

[Eranga]

Yes pal that's true. Even me never touch the IDE. I thought after answering you test it ans says that. Sorry if I say some annoying thing there.

[Eranga]

Seems all are silent here. I don't want to be like that. So here I'm,

Code:

public interface myInterface extends intOne, intTwo {
    private float temp = 12.234F;

    int addIntegers(int i, int j);
}

My question is, the above code is valid or not. Please don't compile it before answering.

[rjuyal]

i guess all variables in interface should be public staic final, so it should not compile.

[Eranga]

[Yep, it's right. Because interface body only can contain constant declarations only. And if you want that set of modifiers can be omitted.

Next quiz?