Chapter 3 Book Quiz

Question 1

The if statement is an example of a .
a. sequence structure
b. decision structure
c. pathway structure
d. class structure

Answer 1

b. decision structure
Explanation: The if statement is used to make decisions based on a boolean condition, which is why it is classified as a decision structure.

Question 2

This type of expression has a value of either true or false .
a. binary expression
b. decision expression
c. unconditional expression
d. boolean expression

Answer 2

d. boolean expression
Explanation: A boolean expression is one that evaluates to either true or false.

Question 3

> , < , and == are .
a. relational operators
b. logical operators
c. conditional operators
d. ternary operators

Answer 3

a. relational operators
Explanation: Relational operators compare two values and return a boolean result, such as >, <, and ==.

Question 4

&& , || , and ! are .
a. relational operators
b. logical operators
c. conditional operators
d. ternary operators

Answer 4

b. logical operators
Explanation: These operators (&&, ||, and !) are used to combine or negate boolean expressions in Java.

Question 5

This is an empty statement that does nothing.
a. missing statement
b. virtual statement
c. null statement
d. conditional statement

Answer 5

c. null statement
Explanation: A null statement, also called an empty statement, does nothing and is represented by a semicolon ;.

Question 6

To create a block of statements, you enclose the statements in these.
a. parentheses ()
b. square brackets []
c. angled brackets <>
d. braces {}

Answer 6

d. braces {}
Explanation: A block of code (or a compound statement) is enclosed in braces {}.

Question 7

This is a boolean variable that signals when some condition exists in the program.
a. flag
b. signal
c. sentinel
d. siren

Answer 7

a. flag
Explanation: A flag is a boolean variable used to track or signal when a particular condition is true or false.

Question 8

How does the character ‘A’ compare to the character ‘B’?
a. ‘A’ is greater than ‘B’
b. ‘A’ is less than ‘B’
c. ‘A’ is equal to ‘B’
d. You cannot compare characters

Answer 8

b. ‘A’ is less than ‘B’
Explanation: Characters in Java are compared based on their Unicode values, and ‘A’ has a lower Unicode value than ‘B’.

Question 9

This is an if statement that appears inside another if statement.
a. nested if statement
b. tiered if statement
c. dislodged if statement
d. structured if statement

Answer 9

a. nested if statement
Explanation: A nested if statement is an if statement that appears inside another if statement.

Question 10

An else clause always goes with .
a. the closest previous if clause that doesn’t already have its own else clause
b. the closest if clause
c. the if clause that is randomly selected by the compiler
d. none of these

Answer 10

a. the closest previous if clause that doesn’t already have its own else clause
Explanation: The else clause is associated with the closest if that does not already have its own else.

Question 11

When determining whether a number is inside a range, it’s best to use this operator.
a. &&
b. !
c. ||
d. ? :

Answer 11

a. &&
Explanation: The && (logical AND) operator is used to combine conditions, which is ideal when checking if a number lies within a specific range.

Question 12

This determines whether two different String objects contain the same string.
a. the == operator
b. the = operator
c. the equals method
d. the stringCompare method

Answer 12

c. the equals method
Explanation: The equals method is used to compare the contents of two String objects for equality.

Question 13

The conditional operator takes this many operands.
a. one
b. two
c. three
d. four

Answer 13

c. three
Explanation: The conditional (ternary) operator ? : takes three operands: the boolean condition, the value if true, and the value if false.

Question 14

This section of a switch statement is branched to if none of the case expressions match the switch expression.
a. else
b. default
c. case
d. otherwise

Answer 14

b. default
Explanation: The default section of a switch statement is executed when no case matches the value of the switch expression.

Question 15

You can use this method to display formatted output in a console window.
a. Format.out.println
b. Console.format
c. System.out.printf
d. System.out.formatted

Answer 15

c. System.out.printf
Explanation: The System.out.printf method is used to display formatted output to the console in Java.

Question 16

TRUE OR FALSE: The = operator and the == operator perform the same operation.

Answer 16

FALSE
Explanation: The = operator is used for assignment, while the == operator is used for comparison.

Question 17

TRUE OR FALSE: A conditionally executed statement should be indented one level from the if clause.

Answer 17

TRUE
Explanation: Indentation is used to improve readability, and conditionally executed statements are typically indented one level from the if clause.

Question 18

TRUE OR FALSE: All lines in a conditionally executed block should be indented one level.

Answer 18

TRUE
Explanation: Indenting all lines in a conditionally executed block helps improve readability and structure.

Question 19

TRUE OR FALSE: When an if statement is nested in the if clause of another statement, the only time the inner if statement is executed is when the boolean expression of the outer if statement is true .

Answer 19

TRUE
Explanation: The inner if statement will only execute if the condition of the outer if statement is true.

Question 20

TRUE OR FALSE: When an if statement is nested in the else clause of another statement, the only time the inner if statement is executed is when the boolean expression of the outer if statement is true .

Answer 20

FALSE
Explanation: The inner if in the else block will execute only if the condition of the outer if statement is false.

Question 21

TRUE OR FALSE: The scope of a variable is limited to the block in which it is defined.

Answer 21

TRUE
Explanation: A variable’s scope refers to the part of the program where it can be accessed, which is limited to the block or method where it is defined.

Question 22

Find the errors in the following code:
1.
// Warning! This code contains ERRORS!
if (x == 1);
y = 2;
else if (x == 2);
y = 3;
else if (x == 3);
y = 4;

Answer 22

Corrected Code: if (x == 1) {
y = 2;
} else if (x == 2) {
y = 3;
} else if (x == 3) {
y = 4;
}
Semicolon after if/else if conditions: The semicolon causes the code block to terminate prematurely, so the code within the if, else if, and else statements doesn’t execute correctly.
Correct use of braces {}: To group statements within if/else if conditions, braces must be used.

Question 23

// Warning! This code contains an ERROR!
if (average = 100)
System.out.println(“Perfect Average!”);

Answer 23

corrected code: if (average == 100)
System.out.println(“Perfect Average!”);

Error: Using the assignment operator (=) instead of the equality operator (==) in the if condition.

Question 24

// Warning! This code contains ERRORS!
if (num2 == 0)
System.out.println(“Division by zero is not
possible.”);
System.out.println(“Please run the program
again “);
System.out.println(“and enter a number besides
zero.”);
else
Quotient = num1 / num2;
System.out.print(“The quotient of “ + Num1);
System.out.print(“ divided by “ + Num2 + “ is
“);
System.out.println(Quotient)

Answer 24

Corrected Code:
// Warning! This code contains ERRORS!
if (num2 == 0) {
System.out.println(“Division by zero is not possible.”);
System.out.println(“Please run the program again “);
System.out.println(“and enter a number besides zero.”);
} else {
Quotient = num1 / num2;
System.out.print(“The quotient of “ + num1);
System.out.print(“ divided by “ + num2 + “ is “);
System.out.println(Quotient);
}

Used curly braces {} to group statements inside the if and else blocks.
Corrected variable names to match the case (num1 and num2).
Added a missing semicolon at the end of the System.out.println(Quotient) statement.
Fixed formatting for better readability.

Question 25

// Warning! This code contains ERRORS!
switch (score)
{
case (score > 90):
grade = ‘A’;
break;
case(score > 80):
grade = ‘b’;
break;
case(score > 70):
grade = ‘C’;
break;
case (score > 60):
grade = ‘D’;
break;
default:
grade = ‘F’;
}

Answer 25

Corrected Code:
Instead of using boolean conditions in the case labels, we can use ranges and replace the switch statement with an if-else chain. Here’s how to modify the program:

// Corrected code
if (score > 90) {
grade = ‘A’;
} else if (score > 80) {
grade = ‘B’;
} else if (score > 70) {
grade = ‘C’;
} else if (score > 60) {
grade = ‘D’;
} else {
grade = ‘F’;
}

A switch statement is designed to work with constant values or simple expressions (like integers, characters, or enums), not with complex boolean expressions like score > 90. Hence, the most appropriate solution for this type of range-based logic is an if-else structure.

Question 26

The following statement should determine whether x is not
greater than 20. What is wrong with it?
if (!x > 20)

Answer 26

if (!(x > 20))
This checks if x is not greater than 20 by applying the negation to the expression x > 20. If x > 20 is false, then !(x > 20) will be true, and the block will execute.

Problem: The ! operator cannot be applied to a numeric value like x.
Solution: Use the comparison operator <= to check if x is not greater than 20, or use !(x > 20) to apply the negation correctly.

Question 27

The following statement should determine whether count is
within the range of 0 through 100. What is wrong with it?
if (count >= 0 || count <= 100)

Answer 27

Correcting the Statement:
To check if count is within the range of 0 through 100, you need to use the logical AND (&&) operator, not the OR (||) operator, because you want both conditions to be true at the same time. Here’s the corrected version:

if (count >= 0 && count <= 100)

Problem: The OR operator (||) was used, which caused the condition to always be true.
Solution: Use the AND operator (&&) to ensure that count is both greater than or equal to 0 and less than or equal to 100.

Question 28

The following statement should determine whether count is
outside the range of 0 through 100. What is wrong with it?
if (count < 0 && count > 100)

Answer 28

Correcting the Statement:
To determine whether count is outside the range of 0 through 100, you should use the logical OR (||) operator. This way, you check if count is either less than 0 or greater than 100.

Here’s the corrected version:

if (count < 0 || count > 100)

Problem: The conditions count < 0 && count > 100 are contradictory and will never be true at the same time.
Solution: Use the OR (||) operator to check if count is less than 0 or greater than 100.

Question 29

The following statement should assign 0 to z if a is less than
10; otherwise, it should assign 7 to z . What is wrong with it?
z = (a < 10) : 0 ? 7;

Answer 29

Corrected Version:
To fix the statement and assign 0 to z if a is less than 10, otherwise assign 7 to z, you should write:

z = (a < 10) ? 0 : 7;

Problem: The ternary operator syntax was incorrect because the order of operands was wrong.
Solution: Use the correct syntax: condition ? value_if_true : value_if_false;

Question 30

Assume that partNumber references a String object. The
following if statement should perform a case-insensitive
comparison. What is wrong with it?
if (partNumber.equals(“BQ789W4”))
available = true;

Answer 30

Corrected code:
if (partNumber.equalsIgnoreCase(“BQ789W4”))
available = true;

Problem: The equals() method performs a case-sensitive comparison.
Solution: Use equalsIgnoreCase() to perform a case-insensitive comparison

Question 31

What is wrong with the following code?
double value = 12345.678;
System.out.printf(“%.2d”, value);

Answer 31

Corrected Code:
If you want to print the double value rounded to two decimal places, you should use:

double value = 12345.678;
System.out.printf(“%.2f”, value);

The d specifier is for integers, and the f specifier is for floating-point numbers. For formatting a double, you should use %.2f instead of %.2d.