[Java知识库]Java 面向对象程序设计 错题整理 chapter 10

7.

What?is?the?output?of?the?following?code?

public?class?Test?{

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

????java.math.BigInteger?x?=?new?java.math.BigInteger("3");

????java.math.BigInteger?y?=?new?java.math.BigInteger("7");

????x.add(y);

????System.out.println(x);

??}

}

单选题?(2?分)?2 分

1. ?A.

   4

2. ?B.

   10

3. ?C.

   3

4. ?D.

   11

9.

Which?of?the?following?statements?convert?a?double?value?d?into?a?string?s?

?回答错误

单选题?(2?分)?0 分

1. ?A.

   s?=?(Double.valueOf(s)).toString();

2. ?B.

   s?=?new?Double(d).stringOf();

3. ?C.

   s?=?(new?Double(d)).toString();

4. ?D.

   s?=?String.stringOf(d);

10.

__________?returns?a?string.

多选题?(2?分)?2 分

1. ?A.

   String.valueOf(false)

2. ?B.

   String.valueOf(new?char[]{'a',?'b',?'c'})

3. ?C.

   String.valueOf(12.53)

4. ?D.

   String.valueOf(123)

11.

What?is?the?output?of?Integer.parseInt("10",?2)?

单选题?(2?分)?2 分

1. ?A.

   1;

2. ?B.

   2;

3. ?C.

   Invalid?statement;

4. ?D.

   10;

13.

Suppose?s1?and?s2?are?two?strings.?Which?of?the?following?statements?or?expressions?are?incorrect?

多选题?(2?分)?2 分

1. ?A.

   int?i?=?s1.length

2. ?B.

   s1.charAt(0)?=?'5'

3. ?C.

   String?s3?=?s1?+?s2

4. ?D.

   String?s?=?new?String("new?string");

5. ?E.

   s1?>=?s2

17.

In?JDK?1.5,?you?may?directly?assign?a?primitive?data?type?value?to?a?wrapper?object.?This?is?called?______________.

单选题?(2?分)?2 分

1. ?A.

   auto?boxing

2. ?B.

   auto?conversion

3. ?C.

   auto?casting

4. ?D.

   auto?unboxing

20.

Which?of?the?following?is?the?correct?statement?to?return?a?string?from?an?array?a?of?characters?

单选题?(2?分)?2 分

1. ?A.

   String.toString(a)

2. ?B.

   toString(a)

3. ?C.

   convertToString(a)

4. ?D.

   new?String(a)

22.

Which?of?the?following?statements?will?convert?a?string?s?into?i?of?int?type?

?回答错误

多选题?(2?分)?0 分

1. ?A.

   i?=?(new?Integer(s)).intValue();

2. ?B.

   i?=?(int)(Double.parseDouble(s));

3. ?C.

   i?=?Integer.valueOf(s);

4. ?D.

   i?=?Integer.parseInt(s);

5. ?E.

   i?=?Integer.valueOf(s).intValue();

28.

___________?is?attached?to?the?class?of?the?composing?class?to?denote?the?aggregation?relationship?with?the?composed?object.

单选题?(2?分)?2 分

1. ?A.

   An?empty?diamond

2. ?B.

   An?empty?oval

3. ?C.

   A?solid?diamond

4. ?D.

   A?solid?oval

30.

Which?of?the?following?is?an?object?

多选题?(2?分)?2 分

1. ?A.

   new?String("abc");

2. ?B.

   343

3. ?C.

   new?Date()

4. ?D.

   "abc"

38.

What?is?displayed?by?the?following?code?

????System.out.print("A,B;C".replaceAll(",;",?"#")?+?"?");

????System.out.println("A,B;C".replaceAll("[,;]",?"#"));

单选题?(2?分)?2 分

1. ?A.

   A#B#C?A#B#C

2. ?B.

   A?B?C?A#B#C

3. ?C.

   A?B?C?A?B?C

4. ?D.

   A,B;C?A#B#C

41.

Which?of?the?following?statements?are?correct?

?回答错误

多选题?(2?分)?0 分

1. ?A.

   new?java.math.BigInteger(343);

2. ?B.

   new?java.math.BigDecimal("343.445");

3. ?C.

   new?java.math.BigDecimal(343.445);

4. ?D.

   new?java.math.BigInteger("343");

42.

Assume?s?is?"ABCABC",?the?method?__________?returns?an?array?of?characters.

单选题?(2?分)?2 分

1. ?A.

   s.toCharArray()

2. ?B.

   s.toChars()

3. ?C.

   String.toChars()

4. ?D.

   String.toCharArray()

5. ?E.

   toChars(s)

45.

What?is?the?printout?of?the?following?code?

????String?s1?=?"Welcome?to?Java";

????String?s2?=?"Welcome?to?Java";

????System.out.println("s1?==?s2?is?"?+?s1?==?s2);

单选题?(2?分)?2 分

1. ?A.

   s1?==?s2?is?true

2. ?B.

   true

3. ?C.

   false

4. ?D.

   s1?==?s2?is?false

46.

Which?of?the?following?statements?will?convert?a?string?s?into?a?double?value?d?

单选题?(2?分)?2 分

1. ?A.

   d?=?Double.parseDouble(s);

2. ?B.

   All?of?the?above.

3. ?C.

   d?=?Double.valueOf(s).doubleValue();

4. ?D.

   d?=?(new?Double(s)).doubleValue();

47.

Which?of?the?following?statements?is?correct?

多选题?(2?分)?2 分

1. ?A.

   Integer.parseInt("345",?8);

2. ?B.

   Integer.parseInt("12",?2);

3. ?C.

   Integer.parseInt(100);

4. ?D.

   Integer.parseInt("100");

5. ?E.

   Integer.parseInt(100,?16);

48.

What?is?displayed?by?the?following?code?

????System.out.print("Hi,?ABC,?good".matches("ABC?")?+?"?");

????System.out.println("Hi,?ABC,?good".matches(".*ABC.*"));

单选题?(2?分)?2 分

1. ?A.

   false?false

2. ?B.

   true?false

3. ?C.

   true?true

4. ?D.

   false?true

50.

Which?of?the?following?classes?are?immutable?

多选题?(2?分)?2 分

1. ?A.

   Integer

2. ?B.

   BigInteger

3. ?C.

   Double

4. ?D.

   String

5. ?E.

   BigDecimal