Chapter 2: Elementary programming

Question 1

Data type

Answer 1

specifies the type of value stored in a variable(int, string, boolean, etc.)

Question 2

Fundamental type

Answer 2

represents numbers, characters, and Boolean values

Question 3

Variable

Answer 3

represents a stored value in a computers memory

Question 4

Pseudocode

Answer 4

nature language + coding syntax(in this case Java)

Question 5

double

Answer 5

used to declare a floating point number

Question 6

char

Answer 6

used to declare a single character value such as “A”, “b”

Question 7

String

Answer 7

used to declare multiple characters. like a sentence

Question 8

What is a java object

Answer 8

A Java object is an instance of a class. Meaning that objects are formed under classes and have an identity, behavior, and a state.

Question 9

import java.util.*;

Answer 9

Wildcard Import. imports all the classes in a package by using the asterisk as the wildcard.

Question 10

Scanner input = new Scanner(System.in)

Answer 10

creates a Scanner object and assigns its reference to the variable ‘input’.

Question 11

prompt

Answer 11

something that directs a user to enter input. A program should always tell a user what to enter when expecting input from the keyboard.

Question 12

double radius = input.nextDouble();

Answer 12

this line will read the number (hopefully a number) inputed by the user and assign the value to ‘radius’.

Question 13

IPO

Answer 13

Stands for input, process, and output and are the typical three steps for most simple programs in the text.

Question 14

Wildcard import

Answer 14

imports all classes in the package by using the asterisk as the wildcard

Question 15

Specific import

Answer 15

imports a specific/single class.

Question 16

the correct method to read a real number is with a scanner object labeled ‘input’ is…

Answer 16

input.nextDouble()

Question 17

identifiers

Answer 17

names of varaibles, classes interface, or packages

Question 18

Identifiers must follow what rules?

Answer 18

1. sequence of characters that consists of letters, digits, underscores, and dollar signs.
2. an identifiers cannot start with a digit.
3. Cannot be a reserve word
4. Can be any length

Question 19

Evaluate the statement:

“Every letter in a Java keyword is lowercase.”

Answer 19

True.

Question 20

Which of the following are correct names for variables according to Java naming conventions?

1. radius
2. Radius
3. RADIUS
4. findArea
5. FindArea

Answer 20

1 and 4.

Single word variables are in lowercase while multiple word variables follow “camelNamingConvention” in which the first word is lowercasae and the subsequent words have their first letter capitalized.

Question 21

Constant

Answer 21

Represents a permanent data that never changes.

Question 22

Constants are also known as what in Java…

Answer 22

Final ‘Variable’

Question 23

what is the syntax for decalring a constant?

Answer 23

final datatype CONSTANTNAME = value;

Question 24

Declare an int constant SIZE with value 20

Answer 24

final int SIZE = 20

Question 25

Suppose m and r are integers. Write a Java expression for mr 2 to obtain a floating-point result.

Answer 25

1. 0 * m * (r * r).
   * using the floating point number 1.0 makes the product of the equation a floating point.*

Question 26

Math.pow(2, 3) returns what type of datatype?

Answer 26

double: 8.0

Question 27

Math.pow(4, 1 / 2) returns

Answer 27

1.0

Question 28

Assume that an int variable x that has already been declared , and initialized to a non-negative value .

Write an expression whose value is the last (rightmost) digit of x.

Answer 28

public static void main(String[] args) {

int x = 14;

System.out.println(x % 10.0); }

the underlined section is the expression.

Question 29

Declare and initialize the following variables:

int monthOfYear, initialized to the value 11

long companyRevenue, initialized to the value 5666777

int firstClassTicketPrice, initialized to the value 6000

long totalPopulation, initialized to the value 1222333

Answer 29

int monthOfYear = 11;
long companyRevenue = 5666777;
int firstClassTicketPrice = 6000;
long totalPopulation = 1222333;

Question 30

What is a literal?

Answer 30

A constant value that appears directly in the program.

Question 31

How would 1.23456 x 10^2 be written in Java?

Answer 31

1.23456e2 or 1.23456E2

Question 32

How many accurate digits are stored in a floating and double point value?

Answer 32

A float contains 7-8 number of accurate digits whereas a double contains 15-17.

Question 33

Which of the following are correct literals for floating-point numbers?

12.3, 12.3e+2, 23.4e-2, -334.4, 20.5, 39F, 40D

Answer 33

All are viable options.

Question 34

Which of the following are the same as 52.534?

5.2534e+1, 0.52534e+2, 525.34e-1, 5.2534e+0

Answer 34

5.2534e+1, 0.52534e+2, 525.34e-1

Question 35

Which of the following are correct literals?

5_2534e+1, _2534, 5_2, 5_

Answer 35

5_234e+1 & 5_2

Question 36

Write a literal representing the Long value 12 billion

Answer 36

12000000000L

Question 37

Write a hexadecamial integer literal with the value 15

Answer 37

0xf

Question 38

The expression 4 + 20/(3-1) *2 is evaluated into…

Answer 38

24.

1. (3-1) = 2
2. 20/2 = 10
3. 10 * 2 = 20
4. 20 + 4 = 24

Question 39

How to display the current UTC hour?

Answer 39

System.currentTimeMillis()/1000/60/60 %24

Question 40

What is the output of…

double a = 6.5

a += a + 1

System.out.println(a)

Answer 40

14…

The code is saying a is equal to 6.5. Then the second line is saying “a” is assigned the value a = a + a + 1 which is 6.5 + 6.5 + 1.

So 14 would be printed out onto the terminal.

Question 41

What is the output of…

a = 6;

a /= 2;

System.out.println(a)

Answer 41

3 will be printed on the terminal. The code, is regular written math/english would be written as…

a is equal to 6.

a is equal to 6 divided by 2.

Print the output of the value of “a”.

Question 42

What is the value of x after the following statements:

int x = 2

int y = 1

x *= y + 1

Answer 42

x = 4

It may be tempting to say 3 but remeber, the augmented assignment operators are performed last in the order.

Question 43

What is the output of the following code:

int a = 6;

int b = a++;

System.out.println(a);

System.out.println(b);

a = 6;

b = ++a

System.out.println(a)

System.out.println(b)

Answer 43

7

6

7

7

Question 44

Preincrement

Answer 44

Increase the value by 1 AND return the NEW value.

Question 45

Postincrement

Answer 45

Decrease the value by 1 AND return the OLD value.

Question 46

Predecrement

Answer 46

Decrease the value by 1 AND return the NEW value.

Question 47

Postdecrement

Answer 47

Decrease the value by 1 AND return the old value.

Question 48

What are the operands in this expression:

result = a + b + c;

Answer 48

a,b,c

Question 49

what are the operators in this expression;

result = a + b - c;

Answer 49

+,-

Question 50

Are the statements equivalent?

number += 1;

number = number + 1;

number++;

++number;

Answer 50

YES. AS STATEMENTS THEY ARE THE SAME AS EXPRESSIONS THEY WOULD NOT BE.

Question 51

What does “sum” become after this statement?

int sum = 0;

sum += 4.5;

Answer 51

sum becomes 4 since it is type int.

sum += 4.5; is the same as sum = (int)(sum + 4.5);

Question 52

To assign a double varibale, d, to a float variable x, you write…

Answer 52

x = (float)d;

Question 53

Which one of these assignment statements is illegal? Why?

float f = -34;
int t = 23;
short s = 10;
int t = 4.5;

Answer 53

int t = 4.5;

This is because you cannot assign a floating point number (larger datatype) to a smaller datatype (integer) without explicit type casting.

Question 54

What will be the output of the following code:

System.out.println((double)(5/2));

Answer 54

2.0