Module 01: Primitive Types

Question 1

Which of the following is not a primitive type?

1. int
2. double
3. String
4. boolean
5. char

Answer 1

3. String

Question 2

Which of the following statements is true about variables?

1. The memory associated with a variable of a primitive type holds an actual primitive value.
2. When a variable is declared final, its value can only be changed through a direct reassignment.
3. A variable originally created as an int can be changed to store a double through casting.
4. All of these choices are true

Answer 2

1. The memory associated with a variable of a primitive type holds an actual primitive value

Question 3

What is the value of x after this code runs?

int x = 5;

x = 10;

x = 4;

Answer 3

4

Question 4

What is the proper syntax to declare and initialize a variable called temperature to have the value 70.4?

1. int temperature = 70.4;
2. double temperature = 70.4;
3. temperature = 70.4;
4. dbl temperature = 70.4;
5. temperature = (double) 70.4

Answer 4

2. double temperature = 70.4;

Question 5

What is the result of this expression?

(int) (5 + 2 / 3 + 1)

Answer 5

6

Question 6

Which expression returns the 1’s place of an integer x?

1. x % 10
2. x / 10
3. x % 100
4. x + 1

Answer 6

1. x % 10

Question 7

What is the value of myInteger after this line of code is executed?

int myInteger = (int) 5.6;

Answer 7

5

Question 8

What output will be produced by

System.out.println(“Hello”); System.out.println(“Karel”);

Answer 8

Hello

Karel

Question 9

Refer to the following code segment:

• double myDouble = 1/4;*
• System.out.println(“1 / 4 = “ + myDouble);*

The output of the code is:

1 / 4 = 0.0

The student wanted the output to be:

1 / 4 = 0.25

Which change to the first line of their code segment would get the student the answer that they wanted?

1. int myDouble = 1/4;
2. double myDouble = (double) 1/4;
3. double myDouble = (int) 1/4;
4. double myDouble = (int) (1.0/4.0);

Answer 9

2. double myDouble = (double) 1/4;

Question 10

What is the result of this expression?

4 + 8 * 3 / 4 + 5 % 2

Answer 10

11

Question 11

Joe’s Pizza is creating a program that will calculate the total amount of money an employee earns each week. Employees are paid by the hour and only work in 1 hour increments. Salaries start at minimum wage, but employees get a $0.50 raise after the first month. Which variables would be the best to store the hours and salary of the employees?

(1) double hours
int salary

(2) int hours
double salary

(3) boolean hours
double salary

(4) int hours
int salary

(5) double hours
boolean salary

Answer 11

(2) int hours
double salary

Question 12

What will the following code print?

• int n = 5;*
• n ++;*
• n ++;*
• n += n;*
• System.out.println(n);*

Answer 12

14

Question 13

Which of the following would equal 2?

I.

int x = 0;

x ++;

x += x;

II.

int y = 4;

y ++;

y /= 2;

III.

int z = 4;

z += 2;

z /= 2;

1. I Only
2. II Only
3. III Only
4. I and II Only
5. I, II, and III

Answer 13

4. I and II Only

Question 14

Given a and b as properly initialized integers, which of the following will result in a correct calculation with a decimal answer?

1. double y = (double) (a / b);
2. double y = a / b * 1.0;
3. double y = a / b;
4. double y = 1.0 * a / b;

Answer 14

4. double y = 1.0 * a / b;

Question 15

Assume y is a properly initialized positive integer. Which of the following will always result in a value of 1?

1. y ++;
2. y –;
3. y += y;
4. y /= y;
5. y -= y;

Answer 15

4. y /= y;

Question 16

The following code is intended to print 8.

• int x = 23;*
• double y = 3;*
• System.out.println((int)(x / y));*

What is printed and why?

1. 7 because the values of x and y are integers so 23 / 3 evaluated to 7
2. 7 because x / y calculates to 7.66 then the cast to an int results in the value getting truncated to 7
3. 8 because the values of x and y are integers so 23 / 3 evaluated to 8
4. 8 because x / y calculates to 7.66 then the cast to an int results in the value getting rounded up to 8

Answer 16

2. 7 because x / y calculates to 7.66 then the cast to an int results in the value getting truncated to 7

Question 17

What will the output of the following lines of code be?

int x = 10;

int y = x / 4;

System.out.print(“x + y = “);

System.out.print(x + y);

Answer 17

x + y = 12

Question 18

Which of the following print:

Hello Java!

I.

System.out.println(“Hello Java!”);

II.

System.out.print(“Hello Java!”);

III.

System.out.print(“Hello”);

System.out.print(“Java!”);

IV.

System.out.println(“Hello”);

System.out.println(“Java!”);

1. I and II only
2. I, II, and III only
3. I and III only
4. I, II, and IV only
5. I, II, III, and IV

Answer 18

1. I and II only

Question 19

How many lines will be printed with the following statement?

System.out.println(“Hello”);

System.out.println(“ World”);

System.out.print(“Welcome to”);

System.out.print(“Java.”);

Answer 19

3

Question 20

Assume that a, b, and c are all integers with values of 90, 5, and 4 respectively. What would the value of x be in this expression?

int x = a / b / c;

Answer 20

4

Question 21

A financial planner wants to calculate the average rate of return for clients. She does this by dividing the earnedIncome by the principal amount and displays the value as a double. Which of the following will correctly calculate and store the returnRate, assuming earnedIncome and principal are integers?

I. double returnRate = earnedIncome / principal;
II. double returnRate = (double) earnedIncome / principal;
III. double returnRate = (double) (earnedIncome / principal);

1. I only
2. II only
3. III Only
4. II and III only
5. I, II, III

Answer 21

2. II only

Question 22

A teacher has calculated the gradeAverage as a double, but for report cards, she needs to report it rounded to the nearest whole number. Assuming that we round up from 0.5, which of the following will correctly round the gradeAverage?

1. int rcGrade = (int) gradeAverage;
2. int rcGrade = gradeAverage % 0.5;
3. int rcGrade = (int) gradeAverage + 0.5;
4. int rcGrade = (int) (gradeAverage + 0.5);
5. int rcGrade = (int) gradeAverage - 0.5;

Answer 22

4. int rcGrade = (int) (gradeAverage + 0.5);

Question 23

What is the result of the following expression when x is 125?
x % 6

Answer 23

5

Question 24

Given the following, what will be printed out?

int a = 2;

int b = 3;

int c = 4;

System.out.println(a * b + b / a + (a * c / 4.0) * c);

Answer 24

15.0

Question 25

Which of the following values can correctly be saved in a boolean?

True

Yes

1

true

yes

Answer 25

true

Question 26

Look at the following piece of code. Your task is to debug the code. For each correction there should be a comment on or before that line of code telling me how you plan to correct the error.

Answer 26

public static void main(String args [])

{

int num = 2;

// Since int p is an integer, it cannot be a desimal (then it will need to be a double), so it should be int p = 5 or double p = 5.0

int p = 5;

int d = 5;

int m = 2;

double a = 7;

double b = 3.5;

// There needs to be a semicolon at the end of a line of code for the compiler to know that it is the end of a command

double c, f, g, h;

c = a/b;

f = d/m;

g = d%m;

h = d/(double)m;

// There needs to be a quotation mark on the right side of the equal than sign in order for the compiler to know it is a string

System.out.println(“ c = “ + c);

// Assuming that each letter needs to be on a separate line, “println” instead of “print” needs to be used

System.out.println(“ f = “ + f);

// There needs to be a command to add the value of “g” in the string

System.out.println(“ g = “ + g);
System.out.print(“ h =” + h);

}

Question 27

What is a program class?

Answer 27

Program Class: all of the code is inside (wrap it in a pair of curly brackets)

The name of the class should match the name of the Java file

Question 28

What is the main method?

Answer 28

Main Method: point where java program starts execution

Question 29

What is increment and decrement?

Answer 29

Common in programming to want to add one or subtract one to a variable

Instead of having to write:

counter = counter + 1;

//We can write, counter++; As a shortcut!

Example:

int x = 0;

//Add one

x++; > 1

// Subtract one x–; > 0

Question 30

What are shortcuts?

Answer 30

Question 31

What are packages?

Answer 31

Packages are used to group code into a folder for easy use

Question 32

What is Scanner class?

Answer 32

A calss within java.util. It contains code specifically designed to help with user input

Question 33

What is variable.nextLine()?

Answer 33

Allows user to input String values

Question 34

What is variable.nextInt()?

Answer 34

Allows users to input int values

Question 35

What is variable.nextDouble()?

Answer 35

Allows users to input double

Question 36

What is the input skeleton for the scanner class?

Answer 36

• java.util: package
  
  • Used to group code into a folder for easy use
  • Scanner: class within java.until
• Scanner input = new Scanner(System.in): Initializes scanner

Question 37

What is casting?

Answer 37

• Casting is turning something of one type into another type!
• Add the type you want in between the parentheses to cast to that type

int x = (int)5.3 > 5

// Add the type you want in between the parentheses to cast to that type

Question 38

How do you cast a double to an int?

Answer 38

Question 39

How do you cast an int to a double?

Answer 39

Question 40

How does rounding when casting work?

Answer 40

Casting can also be used to round double values to the closest integer using (int)(x + 0.5)

• x will then be closest to the nearest integer
• ints round down
  
  • If the decimal is 0.5 or greater, this will round up
  • If the decimal is less than 0.5, it will round down

double x = 2.0;

int y = (int)(x+0.5) > 2

double x = 2.8;

int y = (int)(x+0.5) > 3

Casting can also be used to round negative double value to the closest integer using (int)(x - 0.5):

double x = -2.0;

int y = (int)(x-0.5); > -2

// -2.5

double x = -2.8;

int y = (int)(x-0.5); > -3

// -3.3

Question 41

What are integer limits?

Answer 41

Integer.MIN_Value = -2,147,483,648

Integer.MIAX_Value = 2,147,483,648

int min = Integer.MIN_Value int

max = Integer.MAX_Value