Unit 1: Primitive Types

What will this code segment output?

System.out.println("Hello");
System.out.println("World");

Hello
World

Which code segment will print "Hello Karel" to the screen in Java?

System.out.println("Hello Karel");

What will this code segment output?


public class Printing
{
public static void main(String[] args)
{
System.out.println("*****");
System.out.println("****");
System.out.println("***");
System.out.println("**");
System.out.println("*");
}
}

*****
****
***
**
*

What is the correct syntax for writing the main method in Java?

public static void main(String[] args)
{

}

Which of the following is a proper way to declare and initialize a variable in Java?

int myNumber = 10;

Consider the following code snippet.

public static void main(String args[]){
final int z;
z = 20;
z = 30;
System.out.println(z);
}

What value of z is actually printed?

This code gives an error.

What are the memory values associated with the variables x, y, and z after the code snippet below executes?

int x = 7;
double y = 2.0;
boolean z = false;

x = x + 3;
z = true;

x holds the int value 10, y holds the double value 2.0 and z holds the boolean value true.

Which of the following variable names follows best practices for naming a variable?

numApples

What does the keyword final do?

It prevents variables from being altered.

Which Java Data Type would be the best suited to represent whether or not a student has completed their homework?

boolean

Which Java Data Type would be best suited to represent the amount of money in Barack Obama's bank account.

double

Which Java Data Type would be the best suited to represent the number of days left until the AP Computer Science Exam?

int

What is the result of this expression?

150 % 100

50

Which of the below is NOT a Java arithmetic operator?

#

What will be the output of the following code snippet?

public class Calculator
{
public static void main(String[] args)
{
int first = 7;
int second = 2;
int result = first / second;
System.out.println(result);
}
}

3

What will be the output of the following code snippet and why?

public static void main(String[] args)
{
int num = 2;
int dividend = 5;
dividend /= num;
System.out.println(dividend);
}

The output will be 2 because when two integers are divided in Java, the decimal portion is always truncated.

What will be stored in the variable modulo after running the following code snippet?

public static void main(String[] args)
{
int num = 2;
int modulo = 15;
modulo %= num;
}

1

In Java, the = sign in a statement means

an assignment of the right hand side value to the left hand side variable.

What will be stored in the variable age after this code snippet executes?

public static void main(String[] args)
{
int age = 16;
age++;
age--;
age++;
}

17

Which code snippet below will end with num holding the value 15?

All of the above

What is the correct syntax for creating a Scanner object?

Scanner objectName = new Scanner(System.in);

What is the correct line of code needed to request a whole number from a user?
Assume a Scanner object called input has already been created.

int num = input.nextInt();

What will this java expression evaluate to?

(int) 9.9

9

What is casting in Java?

Casting is turning a value of one type into another type.

What will be the output of the following code snippet?

public class Casting
{
public static void main(String[] args)
{
int total = 100;
int numPeople = 40;
double average;
average = total / (double) numPeople;
System.out.println("Average: " + average);
}
}

Average: 2.5

Which of the following is not a primitive type?

String

Which of the following statements is true about variables?

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

What is the value of x after this code runs?

int x = 5;
x = 10;
x = 4;

4

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

double temperature = 70.4;

What is the result of this expression?

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

6

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

x % 10

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

int myInteger = (int) 5.6;

5

What output will be produced by

System.out.println("Hello");
System.out.println("Karel");

Hello
Karel

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?

double myDouble = (double) 1/4;

What is the result of this expression?

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?

int hours;
double salary;

What will the following code print?

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

14

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;

I and II Only

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

double y = 1.0 * a / b;

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

y /= y;

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?

7 becausex / y calculates to 7.66 then the cast to an int results in the value getting truncated to 7

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);

x + y = 12

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!");

I and II only

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.");

3

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;

4

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);

II only

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?

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

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

x % 6

5

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);

15.0

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

true