58. Given: 

 10. interface Foo{} 

11. class Alpha implements Foo{} 

12. class Beta extends Alpha{}

 13. class Delta extends Beta{ 

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

 15. Beta x = new Beta()； 

16. //insert code here 

17. }

 18. } 

Which code, inserted at line 16, will cause a java.lang.ClassCastException?
(A) Alpha a = x；
(B) Foo f = (Delta)x；
(C) Foo f = (Alpha)x；
(D) Beta b = (Beta)(Alpha)x；

54. Given: 1. package test； 2. 3. class Target{ 4. public String name = "hello"； 5. } What can directly access and change the value of the variable name? (A) any class (B) only the Target class (C) any class in the test package (D) any class that extends Target

55. 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.

56. 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.

57. 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(){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.

59. Given the following directory structure:   (A) If the compile is successful, Utils.class is added to the source directory. (B) The compiler returns an invalid flag error. (C) If the compile is successful, Utils.class is added to the classes directory. (D) If the compile is successful, Utils.class is added to the bigProject directory.

複選題60. Given: 1. package com.company.application； 2. 3. public class MainClass{ 4. public static void main(String[] args){} 5. } And MainClass exists in the /apps/com/company/application directory. Assume the CLASSPATH environment variable is set to "." (current directory). Which two java commands entered at the command line will run MainClass? (Choose two.) (A) java MainClass if run from the /apps directory (B) java com.company.application.MainClass if run from the /apps directory (C) java -classpath /apps com.company.application.MainClass if run from any directory (D) java-classpath . MainClass if run from the /apps/com/company/application directory (E) java -classpath /apps/com/company/application:. MainClass if run from the /apps directory

61. Given two files, GrizzlyBear.java and Salmon.java: 1. package animals.mammals； 2. 3. public class GrizzlyBear extends Bear{ 4. void hunt() { 5. Salmon s = findSalmon()； 6. s.consume()； 7. } 8. } 1. package animals.fish； 2. 3. public class Salmon extends Fish { 4. public void consume() { /* do stuff */ } 5. } If both classes are in the correct directories for their packages, and the Mammal class correctly defines the findSalmon() method, which change allows this code to compile? (A) add import animals. mammals.*； at line 2 in Salmon.java (B) add import animals.fish.*； at line 2 in GrizzlyBearjava (C) add import animals.fish.Salmon.*； at line 2 in GrizzlyBear.java (D) add import animals. mammals.GrizzlyBear*； at line 2 in Salmon.java

62. Given: 31. class Foo{ 32. public int a = 3； 33. public void addFive(){ a += 5； System.out.print("f ")； } 34. } 35. class Bar extends Foo{ 36. public int a = 8； 37. public void addFive(){this.a += 5； System.out.print("b ")；} 38. }Invoked with: Foo f = new Bar()； f.addFive()； System.out.println(f. a)； What is the result? (A) b 3 (B) b 8 (C) b 13 (D) f 3 (E) f 8

複選題67. Given: 10. abstract public class Employee { 11. protected abstract double getSalesAmount()； 12. public double getCommision() { 13. return getSalesAmount() * 0.15； 14. } 15. } 16. class Sales extends Employee { 17. //insert method here 18. } Which two methods, inserted independently at line 17, correctly complete the Sales class? (Choose two.) (A) double getSalesAmount() { return 1230.45； } (B) public double getSalesAmount() { return 1230.45； } (C) private double getSalesAmount() { return 1230.45； } (D) protected double getSalesAmount() { return 1230.45； }

68. Given the following six method names: addListener addMouseListener setMouseListener deleteMouseListener removeMouseListener registerMouseListener How many of these method names follow JavaBean Listener naming rules? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5