76. Given:

 1. class TestA{ 

2. public void start(){System.out.println("TestA")；} 

3. } 

4. public class TestB extends TestA{ 

5. public void start(){System.out.println("TestB")；}

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

7. ((TestA)new TestB()).start()； 

8. } 

9. }

 What is the result?
(A) TestA
(B) TestB
(C) Compilation fails.
(D) An exception is thrown at runtime.

72. Given: 1. package geometry； 2. public class Hypotenuse { 3. public InnerTriangle it = new InnerTriangle()； 4. class InnerTriangle { 5. public int base； 6. public int height； 7. } 8. } Which statement is true about the class of an object that can reference the variable base? (A) It can be any class. (B) No class has access to base. (C) The class must belong to the geometry package. (D) The class must be a subclass of the class Hypotenuse.

73. Given: 10. interface Data { public void load()； } 11. abstract class Info { public abstract void load()； } Which class correctly uses the Data interface and Info class? (A) public class Employee extends Info implements Data {public void load(){ /* do something */ } } (B) public class Employee implements Info extends Data { public void load(){ /* do something */ } } (C) public class Employee extends Info implements Data public void load(){ /* do something */ } public void Info.load(){ /* do something */ } } (D) public class Employee implements Info extends Data { public void Data.load(){ /* do something */ } public void load(){ /* do something */ } } (E) public class Employee implements Info extends Data { public void load(){ /* do something */ } public void Info.load(){ /* do something */ }

複選題74. Which two classes correctly implement both the java.lang.Runnable and the java.lang.Cloneable interfaces? (Choose two.) (A) public class Session implements Runnable, cloneable { public void run()； public Object clone()； } (B) public class Session extends Runnable, Cloneable { public void run(){/* do something */} public Object clone(){/* make a copy */} } (C) public class Session implements Runnable, Cloneable { public void run(){/* do something */} public Object clone() {/* make a copy */} } (D) public abstract class Session implements Runnable, Cloneable { public void run(){/* do something */} public Object clone(){/* make a copy */} } (E) public class Session implements Runnable, implements Cloneable { public void run(){/* do something */} public Object clone() {/* make a copy */} }

75. Given: 11. public interface A{ public void m1()； } 13. class B implements A{ } 14. class C implements A{ public void m1(){}} 15. class D implements A{ public void m1(int x){}} 16. abstract class E implements A {} 17. abstract class F implements A { public void m1(){} } 18. abstract class G implements A { public void m1(int x){} } What is the result? (A) Compilation succeeds. (B) Exactly one class does NOT compile. (C) Exactly two classes do NOT compile. (D) Exactly four classes do NOT compile. (E) Exactly three classes do NOT compile.

77. Given: 11. public static void main(String[] args) {  12. Object obj = new int{1, 2, 3}； 13. int[] someArray = (int[])obj； 14. for (int i: someArray) System.out.print(i + " ")； 15. } What is the result? (A) 1 2 3 (B) Compilation fails because of an error in line 12. (C) Compilation fails because of an error in line 13. (D) Compilation fails because of an error in line 14. (E) A ClassCastException is thrown at runtime.

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.

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.