Java认证模考试题（二）

Question: 6

Which are the valid identifiers in Java?

A. fieldname

B. super

C. 3number

D. #number

E. $number

Explanation:

Valid identifiers in Java can start with a letter, underscore (_), or dollar sign ($), but not with digits or other signs. And identifiers can not be keywords.

　

Correct Answer: A,E 6 of 60

 

 

Question: 7

Which are valid Java keywords?

A. const

B. NULL

C. false

D. this

E. native

Explanation:

All the keywords in Java are lowercase. goto and const are keywords that are not used in Java programming language.

Correct Answer: A,C,D,E 7 of 60

 

 

Question: 8

WWW.CN-MPA.COM 2005-8-16 3:14:42
Which are valid integral expressions in Java?

A. 22

B. 0x22

C. 022

D. 22H

Explanation:

In Java integral has three forms: decimal, octal and hexadecimal. Octal values start with a zero and hexadecimal values start with 0x.

Correct Answer: A,B,C 8 of 60

 

 

Question: 9

Which one of the following ranges of short is correct?

　

　

Explanation:

The length of the short data is 16 bits. The range of short is

The length of the short data is 16 bits. The range of short is

Correct Answer: D 9 of 60

 

Question: 10

 Which one of the following ranges of byte is correct?

　

　

　

　

Correct Answer: B 10 of 60

 

Question: 11

WWW.CN-MPA.COM 2004-5-27 22:14:08
Given the following fragment of code, what are results of i and j after execution?

int i = 1;

int j;

j = i++;

A. 1, 1

B. 1, 2

C. 2, 1

D. 2, 2

Explanation:

Pay attention to the position of the operator ++. In this question, first j is assigned to 1, then the value of i is added to 2.

Correct Answer: C 11 of 60

 

　

 

Question: 12

Which of the following statements are true?

A. >> is the arithmetic right shift operator.

B. >> is the logical right shift operator.

C. >>> is the arithmetic right shift operator.

D. >>> is the logical right shift operator.

Explanation:

There are two right shift operators in Java. They are >> and >>>. >> is the arithmetic(signed) right shift operator and >>> is the logical(unsigned) right shift operator.

Correct Answer: A,D 12 of 60

 

　

 

Question: 13

Which of the following assignments are legal?

A. float a = 2.0

B. double b = 2.0

C. int c = 2

D. long d = 2

Explanation:

In Java the default data type of floating point is double, not float. The assignment from double to float requires an explicit cast.

Correct Answer: B,C,D 13 of 60