sdut java lab7单选

分数 2

作者 翁恺

单位 浙江大学

What is the value of s2 after this code executes?

1. String s1 = "Happy#day";
2. String s2 = s1.substring(1,5);

A.

"Happ"

B.

"Happy"

C.

"appy"

D.

"appy#"

答案正确：C 2 分

2-2

分数 2

作者 翁恺

单位 浙江大学

The result of code below is:

1. public class Test {
2. public static void main(String args[]){
3. String str="ABCDE";
4.           str.substring(3);
5.           str.concat("XYZ");
6. System.out.print(str);
7. }}

A.

DE

B.

DEXYZ

C.

ABCDE

D.

CDEXYZ

答案正确：C  2 分

2-3

分数 2

作者 翁恺

单位 浙江大学

Given code below:

1. String s1 = "Hello";
2. String s2 = "Hell"+"o";
3. String s3 = "Hell";
4. s3 = s3+"o";

Which one below is correct?

A.

s1 == s2 is true, s1 == s3 is true

B.

s1 == s2 is true, s1 == s3 is false

C.

s1 == s2 is false, s1 == s3 is false

D.

s1 == s2 is false, s1 == s3 is true

答案正确：B  2 分

2-4

分数 2

作者 翁恺

单位 浙江大学

For String s;, which statement below is correct?

A.

s is a variable not initialized, and is to be a pointer to an object of String.

B.

At this line, s is a variable holding an object of String.

C.

It will hold an object of String, given s a member variable,.

D.

It will hold an object of String, given s a local variable.

答案正确：A  2 分

2-5

分数 2

作者 翁恺

单位 浙江大学

For code below, the result would be?

1. String s = "  Welcome to Zhejiang University  ";
2. s.trim();
3. System.out.println(s.startsWith("Welcome"));

A.

true

B.

false

C.

Compile error

D.

Run-time exception

答案正确：B  2 分

创建提问

2-6

分数 2

作者 翁恺

单位 浙江大学

For code below, the result would be?

1. String s = "Welcome to Zhejiang University";
2. String[] a = s.split(" ");
3.     System.out.println(a.length);

A.

4

B.

3

C.

Compile error

D.

Run-time exception

答案正确：A  2 分

2-7

分数 2

作者 徐硕博

单位 浙江大学

What is the value of s2 after this code executes?

String s1 = "Happy day";

String s2 = s1.substring(1,5);

，分值为2分。

A.

"Happ"

B.

"Happy"

C.

"appy"

D.

"appy "

答案正确：C  2 分

2-8

分数 2

作者 翁恺

单位 浙江大学

What will be output by the following line?

System.out.println(Math.floor(-2.1));

A.

-2

B.

2.0

C.

-3

D.

-3.0

正确答案：D