招聘試題3<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

1.選擇題(4′×10)：

例題1.(d)

class Parent{

publicvoid method1(){//change here

System.out.println("Parent's method1()");

}

public void method2()

{

System.out.println("Parent's method2()");

method1();

}

}

class Child extends Parent{

public void method1(){

System.out.println("Child's method1()");

}

public static void main(String args[]){

Child p = new Child();//change here

p.method2();

}

}

Choices:

a. Compile time error

b. Run time error

c. prints : Parent's method2()

Parent's method1()

d. prints : Parent's method2()

Child's method1()

例題2：

How can you force garbage collection of an object?

A. Garbage collection cannot be forced

B. Call System.gc().

C. Call System.gc(), passing in a reference to the object to be garbage collected.

D. Call Runtime.gc().

E. Set all references to the object to new values（null, for example）.

例題

3：

Consider the following class:

1. class Test(int i) {

2. void test(int i) {

3. System.out.println(“I am an int.”);

4. }

5. void test(String s) {

6. System.out.println(“I am a string.”);

7. }

8.

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

10. Test t=new Test();

11. char ch='y';

12. t.test(ch);

13. }

14. }

Which of the statements below is true?(Choose one.)

A. Line 5 will not compile, because void methods cannot be overridden.

B. Line 12 will not compile, because there is no version of test() that rakes a char argument.

C. The code will compile but will throw an exception at line 12.

D. The code will compile and produce the following output: I am an int.

E. The code will compile and produce the following output: I am a String.

例題4：

Which of the following lines of code will compile without error？

A.

int i=0;

if (i) {

System.out.println(“Hi”);

}

B.

boolean b=true;

boolean b2=true;

if(b==b2) {

System.out.println(“So true”);

}

C.

int i=1;

int j=2;

if(i==1|| j==2)

System.out.println(“OK”);

D.

int i=1;

int j=2;

if (i==1 &| j==2)

System.out.println(“OK”);

例題5:

Given the following declaration

String s = "hello";

Which are legal code?

A. s >> = 2;

B. char c = s[3];

C. s += "there";

D. int i = s.length();

E. s = s + 3;

例題6 (CDE)

Consider the following code:

Integer s = new Integer(9);

Integer t = new Integer(9);

Long u = new Long(9);

Which test would return true?

A. (s==u)

B. (s==t)

C. (s.equals(t))

D. (s.equals(9))

E. (s.equals(new Integer(9))

例題7(B)

What would be the result of attempting to compile and run the

following piece of code?

public class Test {

public int x;

public static void main(String args[]){

System.out.println("Value is " + x);

}

}

A. The output "Value is 0" is printed.

B. Non-static variable x cannot be referenced from a static context..

C. An "illegal array declaration syntax" compiler error occurs.

D. A "possible reference before assignment" compiler error occurs.

E. An object of type ArrayIndexOutOfBoundsException is thrown.

例題8(AD)

Given the following method body:

{

if (sometest()) {

unsafe();

}

else {

safe();

}

}

The method "unsafe" might throw an IOException (which is not a subclass

of RunTimeException). Which correctly completes the method of

declaration when added at line one?

A. public void methodName() throws Exception

B. public void methodname()

C. public void methodName() throw IOException

D. public void methodName() throws IOException

E. public IOException methodName()

例題9（D）

The following is a program

1) class Exsuper{

2) String name;

3) String nick_name;

4)

5) public ExSuper(String s,String t){

6) name = s;

7) nick_name = t;

8) }

9)

10) public string toString(){

11) return name;

12) }

13) }

14)

15) public class Example extends ExSuper{

16)

17) public Example(String s,String t){

18) super(s,t);

19) }

20)

21) public String toString(){

22) return name +”a.k.a”+nick_name;

23) }

24)

25) public static void main(String args[]){

26) ExSuper a = new ExSuper(“First”,”1st”);

27) ExSuper b = new Example(“Second”,”2nd”);

28)

29) System.out.println(“a is”+a.toString());

30) System.out.println(“b is”+b.toString());

31) }

32) }

What happens when the user attempts to compile and run this program?

` A.

A Compiler error occurs at line 21

B.

An object of type ClassCastException is thrown at line 27

C.

The following output:

a is First

b is second

D.

The following output:

a is First

b is Second a.k.a 2nd

F.

The following output:

a is First a.k.a 1st

b is Second a.k.a 2nd

例題10

(D)

What is written to the standard output given the following statement:

System.out.println(4|7);

Select the right answer:

A.4

B.5

C.6

D.7

E.0

2.填空題(6′×5):

例題1:

Given:

1. public class SwitchTest {

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

3. System.out.println(“value = “ + switchIt(4));

4. }

5. public static int switchIt(int x) {

6. int j = 1;

7. switch (x) {

8. case 1: j++;

9. case 2: j++;

10. case 3: j++;

11. case 4: j++;

12. case 5: j++;

13. default: j++;

14. }

15. return j + x;

16. }

17. }

What is the result?

value = ____

例題2:

Given:

10. int i = 0;

11. for (; i <4; i += 2) {

12. System.out.print(i + “”);

13. }

14. System.out.println(i);

What is the result?

________

例題3:

1. public class test {

2. public static void add3 (Integer i) }

3. int val = i.intValue ( );

4. val += 3;

5. i = new Integer (val);

6. }

7.

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

9. Integer i = new Integer (0);

10. add3 (i);

11. system.out.printIn (i.intValue ( ) );

12. }

13. )

What is the result?

______

例題4:

int index = 1;

boolean[] test = new Boolean[3];

boolean foo= test [index];

What is the result?

______

例題5:

1. public class test {

2. public static string output = “”;

3.

4. public static void foo(int i) {

5.try {

6. if(i==1) {

7. throw new Exception ();

8. }

9. output += “1”;

10. }

11. catch(Exception e) {

12. output += “2”;

13. return;

14. }

15. finally {

16. output += “3”;

17. }

18. output += “4”;

19. )

20.

21. public static void main (string args[]) (

22. foo(0);

23. foo(1);

24.

25. )

26. )

第24行時,output的值為______

3.程式題(15′×2)：

1.36塊磚，36人搬。男搬4，女搬3，兩個小兒擡一磚。要求一次全搬完。需男、女、小兒各若干？

2.自定義一個字串函式，其功能是隨機產生一個由字母和數字組成的任意位數的字串。

答案:

選擇題:

1. D

2. A

點評：在Java中垃圾收集是不能被強迫立即執行的。呼叫System.gc()或Runtime.gc()靜態方法不能保證垃圾收集器的立即執行，因為，也許存在著更高優先順序的執行緒。所以選項B、D不正確。選項C的錯誤在於，System.gc()方法是不接受引數的。選項E中的方法可以使物件在下次垃圾收集器執行時被收集。

3. D

點評：在第12行，16位長的char型變數ch在編譯時會自動轉化為一個32位長的int型，並在執行時傳給void test(int i)方法。

4. BC

點評：選項A錯，因為if語句後需要一個boolean型別的表示式。邏輯操作有^、&、| 和 &&、||,但是“&|”是非法的，所以選項D不正確。

5. CDE

6. CE

7. B

8. AD

9. D

10.D

填空題:

1. 8

2. 0 2 4

3. 0

4. false

5. 13423

程式題:

1.

public class test {

public static void main(String args[]) {

int man = 0;

int woman = 0;

int kids = 0;

for (man = 0; man < 36; man++) {

for (woman = 0; woman < 36; woman++) {

for (kids = 0; kids < 36; kids++) {

if (man * 4 + woman * 3 + kids / 2 == 36 && man + woman + kids == 36 &&

kids % 2 == 0) {

System.out.println("man=" + man + ",woman=" + woman + ",kids=" +

kids);

}

}

}

}

}

}

2.

import java.util.*;

public class test {

public static void main(String args[]) {

Random random = new Random();

int n = random.nextInt(100);

StringBuffer sb = new StringBuffer();

for (int i = 0; i <= n; i++) {

int c = random.nextInt(255);

if ( (c <= '9' && c >= '0') || (c <= 'Z' && c >= 'A') ||

(c <= 'z' && c >= 'a')) {

sb.append( (char) c);

i++;

}

}

System.out.println(sb.toString());

}

}