极之索信息技术(上海)有限公司

选择题 1:关于垃圾收集的哪些叙述是对的。

A.程序开发者必须自己创建一个线程进行内存释放的工作。

B.垃圾收集将检查并释放不再使用的内存。

C.垃圾收集允许程序开发者明确指定并立即释放该内存。

D.垃圾收集能够在期望的时间释放被java对象使用的内存。

2: 1. What will be the result of executing the following code? 2.

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

4. {

5. char digit = 'a';

6. for (int i = 0; i < 10; i++)

7. {

8. switch (digit)

9. {

10. case 'x' :

11. {

12. int j = 0;

13. System.out.println(j);

14. }

15. default :

16. {

17. int j = 100;

18. System.out.println(j);

19. }

20. }

21. }

22. int i = j;

23. System.out.println(i);

24. }

25.

26. Choices:

A.100 will be printed 11 times.

B.The code will not compile because the variable i cannot be declared twice within the main() method.

C.The code will not compile because the variable j cannot be declared twice within the switch statement.

D.None of these.

3:Which statements about Java code security are not true?

A.The bytecode verifier loads all classes needed for the execution of a program.

B.Executing code is performed by the runtime interpreter.

C.At runtime the bytecodes are loaded, checked and run in an interpreter.

D.The class loader adds security by separating the namespaces for the classes of the local file system from those imported from network sources.

4:Which of the following answer is correct to express the value 8 in octal number?

A.010

B.0x10

C.08

D.0x8

5: 1. What will happen when you attempt to compile and run the following code? 2.

3. class Base

4.

5. {

6.

7. int i = 99;

8.

9. public void amethod()

10.

11. {

12.

13. System.out.println("Base.amethod()");

14.

15. }

16.

17. Base()

18.

19. { 20.

21. amethod();

22.

23. }

24.

25. }

26.

27. public class Derived extends Base 28.

29. {

30.

31. int i = -1;

32.

33.

34.

35. public static void main(String argv[]) 36.

37. {

38.

39. Base b = new Derived();

40.

41. System.out.println(b.i);

42.

43. b.amethod();

44.

45. }

46.

47. public void amethod()

48.

49. {

50.

51. System.out.println("Derived.amethod()"); 52.

53. }

54.

55. }

56.

57. Choices:

A.Derived.amethod() -1 Derived.amethod()

B.Derived.amethod() 99

C.Compile time error

D.Derived.amethod()

6: 1. Give the following method: 2. public void method( ){ 3. String a,b;

4. a=new String(“hello world”); 5. b=new String(“game over”);

6. System.out.println(a+b+”ok”);

7. a=null;

8. a=b;

9. System.out.println(a);

10. }

11. In the absence of compiler optimization, which is the earliest point the object a refere

d is definitely elibile to be garbage collection. A.before line 5

B.before line 6

C.before line 7

D.before line 9

7:假定a和b为int型变量,则执行下述语句组后,b的值为

a=1;

b=10;

do

{

b-=a;

a++;

} while (b--<0);

A.9

B.-2

C.-1

D.8

8:软件生命周期的瀑布模型把软件项目分为3个阶段、8个子阶段，以下哪一个是正常的开发顺序?

A.计划阶段、开发阶段、运行阶段

B.设计阶段、开发阶段、编码阶段

C.设计阶段、编码阶段、维护阶段

D.计划阶段、编码阶段、测试阶段

9:A class design requires that a member variable should be accessible only by same package, which modifer word should be used?

A.protected

B.public

C.no modifer

D.private

10: 1. What will happen when you attempt to compile and run the following code?

2.

3. int Output = 10;

4.

5. boolean b1 = false;

6.

7. if((b1 == true) && ((Output += 10) == 20))

8.

9. {

10.

11. System.out.println("We are equal " + Output);

12.

13. }

14.

15. else

16.

17. {

18.

19. System.out.println("Not equal! " + Output);

20.

21. }

22.

23. Choices: