Enum-- jcsp examples

Question 14

Given:

10. class Nav{

11. public enum Direction { NORTH, SOUTH, EAST, WEST }

12. }

13. public class Sprite{

14. // insert code here

15. }

Which code, inserted at line 14, allows the Sprite class to compile?

A. Direction d = NORTH;

B. Nav.Direction d = NORTH;

C. Direction d = Direction.NORTH;

D. Nav.Direction d = Nav.Direction.NORTH;

Answer: D

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Question 17

Given:

1. package sun.scjp;

2. public enum Color { RED, GREEN, BLUE }

1. package sun.beta;

2. // insert code here

3. public class Beta {

4. Color g = GREEN;

5. public static void main( String[] argv)

6. { System.out.println( GREEN); }

7. }

The class Beta and the enum Color are in different packages.

Which two code fragments, inserted individually at line 2 of the Beta

declaration, will allow this code to compile? (Choose two.)

A. import sun.scjp.Color.*;

B. import static sun.scjp.Color.*;

C. import sun.scjp.Color; import static sun.scjp.Color.*;

D. import sun.scjp.*; import static sun.scjp.Color.*;

E. import sun.scjp.Color; import static sun.scjp.Color.GREEN;

Answer: CE

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Question 32

Given:

11. public class Ball {

12. public enum Color { RED, GREEN, BLUE };

13. public void foo() {

14. // insert code here

15. { System.out.println(c); }

16. }

17. }

Which code inserted at line 14 causes the foo method to print RED,

GREEN, and BLUE?

A. for( Color c : Color.values())

B. for( Color c = RED; c <= BLUE; c++)

C. for( Color c; c.hasNext() ; c.next())

D. for( Color c = Color[0]; c <= Color[2]; c++)

E. for( Color c = Color.RED; c <= Color.BLUE; c++)

Answer: A

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Question 33

Given:

10. public class Fabric

11. public enum Color {

12. RED(0xff0000), GREEN(0x00ff00), BLUE(0x0000ff);

13. private final int rgb;

14. Color( int rgb) { this.rgb = rgb; }

15. public int getRGB() { return rgb; }

16. };

17. public static void main( String[] argv) {

18. // insert code here

19. }

20. }

Which two code fragments, inserted independently at line 18, allow the

Fabric class to compile? (Choose two.)

A. Color skyColor = BLUE;

B. Color treeColor = Color.GREEN;

C. Color purple = new Color( 0xff00ff);

D. if( RED.getRGB() < BLUE.getRGB() ) {}

E. Color purple = Color.BLUE + Color.RED;

F. if( Color.RED.ordinal() < Color.BLUE.ordinal() ) {}

Answer: BF

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Question 34

Given:

11. public enum Title {

12. MR(”Mr.”), MRS(”Mrs.”), MS(”Ms.”);

13. private final String title;

14. private Title(String t) { title = t; }

15. public String format(String last, String first) {

16. return title + “ “ + first + “ “ + last;

17. }

18. }

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

20. System.out.println(Title.MR.format(”Doe”, “John”));

21. }

What is the result?

A. Mr. John Doe

B. An exception is thrown at runtime.

C. Compilation fails because of an error in line 12.

D. Compilation fails because of an error in line 15.

E. Compilation fails because of an error in line 20.

Answer: A

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Question 52

Given:

11. public class Test {

12. public enum Dogs {collie, harrier, shepherd};

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

14. Dogs myDog = Dogs.shepherd;

15. switch (myDog) {

16. case collie:

17. System.out.print(”collie “);

18. case default:

19. System.out.print(”retriever “);

20. case harrier:

21. System.out.print(”harrier “);

22. }

23. }

24. }

‘What is the result?

A. harrier

B. shepherd

C. retriever

D. Compilation fails.

E. retriever harrier

F. An exception is thrown at runtime.

Answer: D

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Question 53

Given:

12. public class Test {

13. public enum Dogs {collie, harrier};

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

15. Dogs myDog = Dogs.collie;

16. switch (myDog) {

17. case collie:

18. System.out.print(”collie “);

19. case harrier:

20. System.out.print(”harrier “);

21. }

22. }

23. }

What is the result?

A. collie

B. harrier

C. Compilation fails.

D. collie harrier

E. An exception is thrown at runtime.

Answer: D

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Question 20

Given:

1. interface TestA { String toString(); }

2. public class Test {

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

4. System.out.println(new TestA() {

5. public String toString() { return “test”; }

6. });

7. }

8. }

What is the result?

A. test

B. null

C. An exception is thrown at runtime.

D. Compilation fails because of an error in line 1.

E. Compilation fails because of an error in line 4.

F. Compilation fails because of an error in line 5.

Answer: A