Exam #3 (Fall 2018)

Question 1

What is the output for the following code fragment?

int k = 1, m = 1;
while (k <= 1) {
while(m <= 1) {
if (m == 1 ) {
break;
}
m++;
}
System.out.println("Hi");
k++;
}
System.out.println("Done");

Answer 1

Hi

Done

Question 2

Appending (concatenating) strings is:

a. An expensive operation and an alternative (e.g., StringBuffer) should be used.
b. A cheap operation.
c. An operation that have the same performance as using a StringBuffer.
d. None of the above.

Answer 2

a. An expensive operation and an alternative (e.g., StringBuffer) should be used.

Question 3

When we execute the following code:

System.out.println(3.9 - 3.8 == .10);

a. We will always get true.
b. Getting false is possible as some numbers cannot be represented precisely in binary.
c. An exemption will be thrown.
d. None of the above.

Answer 3

b. Getting false is possible as some numbers cannot be represented precisely in binary.

Question 4

When an exception occurs, Java pops back up the call stack to each of the calling methods to see whether the exception is being handled in a catch block of the method.

True or False.

Answer 4

True

Question 5

In a JUnit test method if you don’t provide an assertion the test is considered to have succeeded.

True or False.

Answer 5

True

Question 6

Creating an array of size 0 is not allowed in Java.

True or False.

Answer 6

True

Question 7

The code in the finally block is executed:

a. Only when no exemption takes place.
b. Always
c. Only when the exemption takes place.
d. None of the above.

Answer 7

b. Always

Question 8

The following class has a privacy leak. Fix the code to remove it (feel free to edit and cross out the code provided).

public class Example {
private StringBuffer data;
public Example(String dataIn) {
data = new StringBuffer();
data.append(dataIn);
     }
public StringBuffer getData() {
return data;
     }
}

Answer 8

getData method will return a copy of data

Question 9

We have an array of string objects and we would like to make a copy of the array so changes to the new array will not affect the original. To make the copy:

a. We need to make a deep copy, otherwise changes in the new array will affect the original.
b. A shallow copy where we only duplicate the array object and not the string objects is enough.
c. A reference copy is enough.
d. None of the above.

Answer 9

b. A shallow copy where we only duplicate the array object and not the string objects is enough.

Question 10

Math.random() returns a value between 0 (inclusive) and less than 1. Complete the following assignment so x is assigned a random integer value between 1(inclusive) and 100 (inclusive). The only function you can use is Math.random().

int x =

Answer 10

(int)(Math.random() * 100) + 1;

Question 11

Rewrite the following code fragment by replacing the if statement with the ternary (? : ) operator.

/* Original Code */
String name;
int y = scanner.nextInt();
if (y > 0) {
name = "Pos";
} else {
name = "Neg";
}

/* Rewritten Code */
String name;
int y = scanner.nextInt();
name =

Answer 11

name = y > 0 ? “Pos” : “Neg”;