84. Given: 

11. class Alpha{

 12. public void foo(){System.out.print("Afoo ")；}

 13. } 

14. public class Beta extends Alpha{ 

15. public void foo(){System.out.print("Bfoo ")；} 

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

 17. Alpha a = new Beta()； 

18. Beta b = (Beta)a； 

19. a.foo()；

20. b.foo()； 

21. }

 22. } 

What is the result?
(A) Afoo Afoo
(B) Afoo Bfoo
(C) Bfoo Afoo
(D) Bfoo Bfoo
(E) Compilation fails.

79. Given classes defined in two different files: 1. package packageA； 2. public class Message{ 3. String getText(){return "text"；} 4. } And: 1. package packageB； 2. public class XMLMessage extends packageA .Message{ 3. String getText(){return "＜msg＞text＜/msg＞"；} 4. public static void main(String[] args) { 5. System.out.println(new XMLMessage().getText())； 6. } 7. } What is the result of executing XMLMessage.main? (A) text (B) Compilation fails. (C) ＜msg＞text＜/msg＞ (D) An exception is thrown at runtime.

80. Given: 3. interface Fish{} 4. class Perch implements Fish{} 5. class Walleye extends Perch{} 6. class Bluegill{} 7. public class Fisherman { 8. public static void main(String[] args) { 9. Fish f = new Walleye()； 10. Walleye w = new Walleye() 11. Bluegill b = new Bluegill()； 12. if(f instanceof Perch) System.out.print("f-p ")； 13. if(w instanceof Fish) System.out.print("w-f ")； 14. if(b instanceof Fish) System.out.print("b-f ")； 15. } 16. } What is the result? (A) w-f (B) f-p w-f (C) w-f b-f (D) f-p w-f b-f (E) Compilation fails.

81. Given: 1. interface DoStuff2{ 2. float getRange(int low, int high)；}  3. 4. interface DoMore { 5. float getAvg(int a, int b, int c)；} 6. 7. abstract class DoAbstract implements DoStuff2, DoMore{} 8. 9. class DoStuff implements DoStuff2{ 10. public float getRange(int x, int y){return 3.14f；}} 11. 12. interface DoAll extends DoMore{ 13. float getAvg(int a, int b, int c, int d)；} What is the result? (A) The file will compile without error. (B) Compilation fails. Only line 7 contains an error. (C) Compilation fails. Only line 12 contains an error. (D) Compilation fails. Only line 13 contains an error. (E) Compilation fails. Only lines 7 and 12 contain errors. F. Compilation fails. Only lines 7 and 13 contain errors. G. Compilation fails. Lines 7, 12, and 13 contain errors.

82. Given: 11. public interface A111{ 12. String s = "yo"； 13. public void method1()；14. } 17. interface B{} 20. interface C extends A111, B{ 21. public void method1()； 22. public void method1(int x)； 23. } What is the result? (A) Compilation succeeds. (B) Compilation fails due to multiple errors. (C) Compilation fails due to an error only on line 20. (D) Compilation fails due to an error only on line 21. (E) Compilation fails due to an error only on line 22.

85. Given: 11. class Animal{public String noise(){return "peep"；}} 12. class Dog extends Animal{ 13. public String noise(){return "bark"；} 14 } 15. class Cat extends Animal{ 16. public String noise(){return "meow"；} 17. } ... 30. Animal animal = new Dog()； 31. Cat cat = (Cat)animal；32. System.out.println(cat.noise())； What is the result? (A) peep (B) bark (C) meow (D) Compilation fails. (E) An exception is thrown at runtime.

87. A team of programmers is involved in reviewing a proposed design for a new utility class, After some discussion, they realize that the current design allows other classes to access methods in the utility class that should be accessible only to methods within the utility class itself. What design issue has the team discovered? (A) Tight coupling (B) Low cohesion (C) High cohesion (D) Loose coupling (E) Weak encapsulation

複選題89. Given: 1. public class Car{ 2. private int wheelCount； 3. private String vin； 4. public Car(String vin){ 5. this.vin = vin； 6. this.wheelCount = 4； 7. } 8. public String drive(){ 9. return "zoom-zoom"； 10. } 11. public String getInfo(){ 12. return "VIN: " + vin + "wheels: " + wheelCount； 13. } 14. } And: 1. public class MeGo extends Car{ 2. public MeGo(String vin){ 3. this.wheelCount = 3； 4. } 5. } What two must the programmer do to correct the compilation errors? (Choose two.) (A) insert a call to this() in the Car constructor (B) insert a call to this() in the MeGo constructor (C) insert a call to super() in the MeGo constructor (D) insert a call to super(vin) in the MeGo constructor (E) change the wheelCount variable in Car to protected

90. Given: 11. interface DeclareStuff{ 12. public static final int EASY = 3； 13. void doStuff(int t)；} 14. public class TestDeclare implements DeclareStuff{ 15. public static void main(String[] args){ 16. int x = 5； 17. new TestDeclare().doStuff(++x)； 18. } 19. void doStuff(int s){ 20. s += EASY + ++s； 21. System.out.println("s " + s)； 22. } 23. } What is the result? (A) s 14 (B) s 16 (C) s 10 (D) Compilation fails. (E) An exception is thrown at runtime.

92. Given a correctly compiled class whose source code is: 1. package com.sun.sjcp； 2. public class Commander { 3. public static void main(String[] args) { 4. // more code here 5. } 6. } Assume that the class file is located in /foo/com/sun/sjcp/, the current directory is /foo/, and that the classpath contains "." (current directory). Which command line correctly runs Commander? (A) java Commander (B) java com.sun.sjcp.Commander (C) java com/sun/sjcp/Commander (D) java -cp com.sun.sjcp Commander (E) java -cp com/sun/sjcp Commander

93. 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；