Sierra/Bates mock for 5.0 question 11

[Steve Weber]

I found a mock exam online somewhere supposedly from the upcoming java 5.0 certification book by K&B containing the following question. The correct answers are supposed to be A, E, and F, but I don't see how E or F could be correct since the sets are untyped, and even if they were, then why wouldn't D be correct? And furthermore, although i can beleive that B is wrong, i could use an explanation as to exactly why.

11. Given:

1. import java.util.*;
1. import java.util.*;
2. public class Fruits {
3. public static void main(String [] args) {
4. Set c1 = new TreeSet();
5. Set o1 = new TreeSet();
6. bite(c1);
7. bite(o1);
8. }
9. // insert code here
10. }
11. class Citrus { }
12. class Orange extends Citrus { }

Which, inserted independently at line 9, will compile? (Choose all that apply.)

A). public static void bite(Set<?> s) { }
B). public static void bite(Set<Object> s) { }
C). public static void bite(Set<Citrus> s) { }
D). public static void bite(Set<? super Citrus> s) { }
E). public static void bite(Set<? super Orange> s) { }
F). public static void bite(Set<? extends Citrus> s) { }
G). Because of other errors in the code, none of these will compile.


The original mock exam can be found at http://www.javabeat.net/javabeat/scjp5/mocks/index.php?page=mock2

[Marcin Skrzek]

Hi Steve,

I think there is mistake in the question. I`ve found the same question, where lines 4. and 5. are slightly different, but given answers are the same -A,E,F.

1. import java.util.*;
2. public class Fruits {
3. public static void main(String [] args) {
4. Set<Citrus> c1 = new TreeSet<Citrus>();
5. Set<Orange> o1 = new TreeSet<Orange>();
6. bite(c1);
7. bite(o1);
8. }
9. // insert code here
10. }
11. class Citrus { }
12. class Orange extends Citrus { }

Does it solve the problem?

[Bert Bates]

Marcin and Steve -

Marcin's got it! We originally had a little disagreement between HTML and the generics < > :roll:

we re-posted the corrected question on the site

thanks!

[Marcus Green]

I think you should look twice at all web based questions with Generics because the angle brackets are going to play merry hell with a lot of mock exams