Java SE 11: Variables & Operators

Question 1

Variables can be initialized with.

A. Only A value

B. A value or without.

C. Without a value

Answer 1

B. A value or without.

Question 2

All variables must have a variable _____

Answer 2

Type

Question 3

You can set the value of a variable without having to declare the type a second time.

True or False

Answer 3

True

String zip;

zip = “83705”;

Question 4

Variables have default value of __________

Answer 4

uninitialized

Question 5

When declaring a string variable the string type must be declared with __________ letter

Answer 5

Uppercase

Question 6

What are the naming guidelines for variables.

Begin each variable with a ______________ letter. Subsequent words should be _______________.

Answer 6

What are the naming guidelines for variables.

Begin each variable with a lowercase letter. Subsequent words should be capitalized.

Ex. myVariable

Question 7

Names are not case-sensitive.

True or False

Answer 7

False

Name are case-sensitive

Question 8

Names cannot include a white space

True or False

Answer 8

True

Question 9

Names should be mnemonic and indicate to the casual observer the intent of the variable.

True or False

Answer 9

True

Question 10

The Undserscore Character _ is a Legal within a vairable name

True or False

Answer 10

False

As of Java SE 9 the underscore character (“_”) is not a legal character and won’t compile in Java SE9 or later

Question 11

What type of variable is followed by name of variable set to a string in quotes

Answer 11

String

String name = “Steve”;

Question 12

What variable type has positive or negative real values containing decibel

Answer 12

double

double price = 9.99

Question 13

Which variable type holds true or false values?

Answer 13

boolean

boolean outOfStock = false;

Question 14

What is the default value of a boolean value?

Answer 14

false

Question 15

String address = “123 Oak St”

Is this variable:

A. Declared
B. Initialized

C. Declared and Initialized

Answer 15

C. Declared and initialized

Question 16

What type of variable is a positive or negative whole number?

Answer 16

Integer

int quantity = 2;

Question 17

How do you declare multiple variables of the same type on one line?

Answer 17

Use comma to separate each variable declaration.

String zip = “83705”, customer = “customer”;

Question 18

What word means to combine multiple strings by joining them

Answer 18

Concatenation

Question 19

What symbol is used for Concatenation?

Answer 19

+

Question 20

IndexOf() and Substring() methods provided by the ______ class in Java

Answer 20

String

Question 21

What does the IndexOf method do.

Answer 21

Gives the location of a character in a string.

Example:

String ipAddress = “122.72.1.45”;

int index1 = ipAddress.indexOf(‘.’);

System.out.println( index1);

System.out.println( index1 + 1);

: 3

: 6

Question 22

What does the substring method do.

Answer 22

You provide it two arguments that are locations in a string and it prints out what’s in-between two points in a string.

String ipAddress = “122.72.1.45”;

int index1 = ipAddress.indexOf(‘.’);

int index2 = ipAddress.indexOf(index1 + 1)

String secondbyte = ipAddress.substring(index +1, index2)

System.out.println(secondbyte);

: 72

Question 23

How do you represents commas in integer (int) numbers

Answer 23

Underscore _

int lowest = -2_147_483_648

Question 24

Can double variable types use scientific notation?

Yes or No

Answer 24

Yes

double scientificValue = 2.345123E22;

Question 25

Can double types using decimal ( . ) notation

Yes or No

Answer 25

Yes

double decimalValue = 3743743948.2134846

Question 26

What are the standard mathematical operators in Java

Answer 26

Plus +

Minus -

Divide /

Multiply *

Question 27

List operators by precedence:

• Multiplication & Division
• Addition
• Parentheses
• Increment and Decrement operators (++ or –)

Answer 27

1. Parentheses - IF there are nested parentheses start from middle and work your way out
2. ++ or –
3. Multiplication and division operators, evaluated from left to right
4. Addition and subtraction operators, evaluated from left tor right

Question 28

You can set __________ by using parentheses ( )

Answer 28

Precedence

Question 29

Which of the following variable declarations and/or initializations are correct?

• string name;
• boolean isComplete = false;
• int count =5; quantity =2;
• boolean isComplete = “true”;

Answer 29

boolean isComplete = false;

Question 30

Given the following variable declarations, what variable type should be used for the product of quantity * price?

int quantity = 2;
double price = 9.99;

• String
• int
• boolean
• double

Answer 30

double

Question 31

Which of the following is an uncommon method of declaring and/or initializing a String?

• String zip = “12345”, country = “USA”;
• String customer;
• String address = “123 Oak St”;
• String hello = new String(“Hello, World”);

Answer 31

String hello = new String(“Hello, World”);

Question 32

Select the operator/character used for concatenating Strings?

• &
• .
• ~
• $
• +
• *

Answer 32

+

Question 33

What is the output of the following code?

String phone = “555-548-1254”;
System.out.println(phone.substring(3, 6));

• 548
• 5-5
• -54
• 48-

Answer 33

-54

Question 34

Which of the following will result in a compile failure?

• double price = 75;
• int quantity = 5.5;
• double price = 25.99;
• int quantity = 10;

Answer 34

int quantity = 5.5;

Question 35

What is the answer of the following division using Java ints?

int a = 7;
int b = 3;
System.out.println(a / b);

• 4
• 2
• 2.3333…
• 3

Answer 35

2

Question 36

Put the following operators in order of evaluation precedence in a mathematical expression.

Multiplication and division operators

Addition and subtraction operators

Operators within a pair of parentheses

Increment and decrement operators (++ or –)

Answer 36

1. Operators within a pair of parentheses
2. Increment and decrement operators (++ or –)
3. Multiplication and division operators
4. Addition and subtraction operators

Question 37

What is the value of the variable c after evaluating the expression?

int c = 50 – 8 * 2 / 4 – 8 + 3

• 16
• 41
• -94
• 61

Answer 37

41

Question 38

Which of the following statements correctly assigns the value “Bob wrote 3 Java programs.” to the msg variable?

▢ msg = name + “ wrote “ + 3 + “ Java programs.”;

▢ msg = name + “ wrote “ + 2+1 + “ Java programs.”;

▢ msg = name + “ wrote “ + num “ Java programs.”;

▢ msg = “Bob wrote “+ (2+1) + “ Java programs.”;

Answer 38

√ msg = name + “ wrote “ + 3 + “ Java programs.”;

▢ msg = name + “ wrote “ + 2+1 + “ Java programs.”;

▢ msg = name + “ wrote “ + num “ Java programs.”;

√ msg = “Bob wrote “+ (2+1) + “ Java programs.”;