#25 to #29 SCJP/OCJP Exams Questions & Answers-

25 Given:

11. abstract class Vehicle { public int speed() { return 0; }

12. class Car extends Vehicle { public int speed() { return 60; }

13. class RaceCar extends Car { public int speed() { return 150; }

...

21. RaceCar racer = new RaceCar();

22. Car car = new RaceCar();

23. Vehicle vehicle = new RaceCar();

24. System.out.println(racer.speed() + ", " + car.speed()

25. + ", " + vehicle.speed());

What is the result?

A. 0, 0, 0

B. 150, 60, 0

C. Compilation fails.

D. 150, 150, 150

E. An exception is thrown at runtime.

Correct Answer: D

26  A team of programmers is reviewing a proposed API for a new utility class. After some discussion, they realize that they can reduce the number of methods in the API without losing any functionality. If they implement the new design , which two OO principles will they be promoting?

A. Looser coupling

B. Tighter coupling

C. Lower cohesion

D. Higher cohesion

E. Weaker encapsulation

F. Stronger encapsulation

Correct Answer: A

27  Given:

5. class Building { }

6. public class Barn extends Building {

7. public static void main(String[] args) {

8. Building build1 = new Building();

9. Barn barn1 = new Barn();

10. Barn barn2 = (Barn) build1;

11. Object obj1 = (Object) build1;

12. String str1 = (String) build1;

13. Building build2 = (Building) barn1;

14. }

15. }

Which is true?

A. If line 10 is removed, the compilation succeeds.

B. If line 11 is removed, the compilation succeeds.

C. If line 12 is removed, the compilation succeeds.

D. If line 13 is removed, the compilation succeeds.

E. More than one line must be removed for compilation to succeed.

Correct Answer: C

28  Given:

21. class Money {

22. private String country = "Canada";

23. public String getC() { return country; }

24. }

25. class Yen extends Money {

26. public String getC() { return super.country; }

27. }

28. public class Euro extends Money {

29. public String getC(int x) { return super.getC(); }

30. public static void main(String[] args) {

31. System.out.print(new Yen().getC() + " " + new Euro().getC());

32. }

33. }

What is the result?

A. Canada

B. null Canada

C. Canada null

D. Canada Canada

E. Compilation fails due to an error on line 26.

F. Compilation fails due to an error on line 29.

Correct Answer: E

29  Assuming that the serializeBanana() and the deserializeBanana() methods will correctly

use Java serialization and given:

13. import java.io.*;

14. class Food implements Serializable {int good = 3;}

15. class Fruit extends Food {int juice = 5;}

16. public class Banana extends Fruit {

17. int yellow = 4;

18. public static void main(String [] args) {

19. Banana b = new Banana(); Banana b2 = new Banana();

20. b.serializeBanana(b); // assume correct serialization

21. b2 = b.deserializeBanana(); // assume correct

22. System.out.println("restore "+b2.yellow+ b2.juice+b2.good);

24. }

25. // more Banana methods go here

50. }

What is the result?

A. restore 400

B. restore 403

C. restore 453

D. Compilation fails.

E. An exception is thrown at runtime.

Correct Answer: C