Java认证模考试题（七）

Question: 38
Person

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---------------

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Student Teacher

There is the following expression in a Java source file:

Person p = new Teacher();

Which of the following expressions return true?

B. p instanceof Student

C. p instanceof Person

D. None of them returns true

Explanation: 

Correct Answer: A,C 38 of 60

 

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Given the following code:

public class Test{

public static void main(String args)

{

String str=new String(World);

char ch={'H','e','l','l','o'};

change(str,ch);

System.out.println(str + and + ch);

}

public static void change(String str, char ch)

{

str=Changed; ch[0]='C';

}

}

What is the result after execution?

B. World and Cello

C. Changed and Hello

D. Changed and Cello

Explanation: 

Correct Answer: B 39 of 60

Question: 40

Double d1 = new Double(1.0);

Double d2 = new Double(1.0);

Float f = new Float(1.0F);

Which results of the following expressions are true?

B. d1.equals(d2)

C. d1 = f

D. f.equals(d1)

Explanation: 

Correct Answer: B 40 of 60