Data Types & Variables (H3)

Question 1

Encoded to a program is stored in memory and can have and be in several types—for example, using a person’s basic information such as name, age, and address.

Answer 1

Data

Question 2

Describe possible operations on the data and the storage method.

Answer 2

Data Types

Question 3

Data Types in Java are Classified in 2:

Answer 3

1. Primitive
2. Abstract

Question 4

Built into the Java language. These are data that are not objects and have no methods. The Java compiler has detailed instructions on the valid operations this data type supports.

Answer 4

Primitive Data Types

Question 5

Primitive Data Types that java defines:

Answer 5

1. byte
2. short
3. int
4. long
5. float
6. double
7. char
8. boolean

Question 6

Java defines Byte, Short, Int, and Long as _. Since Java does not support unsigned integers, these four (4) are signed, positive, and negative values.

Answer 6

Integer Data Types

Question 7

Java does not support unsigned integers as these are mostly used to specify the behaviors of the—

Answer 7

High-order bit

Question 8

defines the sign of an integer value, and Java manages it differently by adding a special “unsigned right shift” operation.

Answer 8

High-order bit

Question 9

Integer Types:

Answer 9

1. byte
2. short
3. int
4. long

Question 10

Default number java knows:

Answer 10

Integer

Question 11

The smallest integer type that represents a small number. It is used to declare a variable holding a natural number between -128 and 127.

Answer 11

Byte

Byte variables are declared by use of the byte

Question 12

Byte range:

Answer 12

-128 to +127 signed

Question 13

An integer is considered _ if its value is between -32768 and 32767. _ data types declare a variable that can hold numbers in that range.

Answer 13

Short

Question 14

Short Range

Answer 14

-32,768 to +32,767

Question 15

A _ number can also be initialized as a Short variable instead of a normal decimal integer.
So, the 3001 integer can be written as 0x4A8. 0x is used in Java to represent:

Answer 15

Hexadecimal

Question 16

This data type can handle larger numbers and is considered the best choice when an integer is needed because when Byte and Short values are used in an expression, they are promoted to _ automatically.

Answer 16

Int

Question 17

Int Range:

Answer 17

-2,147,483,648 to 2,147,483, 647

Question 18

This data type holds a number higher than a regular integer. The _ integer is a variable that can hold a very large number. A capital letter ‘L’ is placed right after the value.

Answer 18

Long

Question 19

also called “real numbers”, and are used when evaluating an expression that needs fractional accuracy such as the computation of square root or a transcendental (sine and cosine)

Answer 19

Floating Point Types

Question 20

Floating Point Types:

Answer 20

1. float
2. double

Question 21

described as a single precision floating point. A real number qualifies as a single precession when it only needs a limited number of bits. Single precision takes half the space of a double precision and is much faster on some processors.

_ are used to represent dollars and cents, so a small letter ‘f’ is placed to the right of the value when initializing the variable.

Answer 21

Float

Question 22

Floats are used to represent dollars and cents, so a _ is placed to the right of the value when initializing the variable.

Answer 22

small letter ‘f’

Question 23

A real number qualifies as a _ when it only needs a limited number of bits. _ takes half the space of a double precision and is much faster on some processors.

Answer 23

single precission

Question 24

_ can be faster than single precision on modern processors that have been optimized for high-speed mathematical calculations. It can handle larger numbers than Float.

Answer 24

Double

Question 25

Character types can be divided into two (2):

Answer 25

(a) A Byte for a character (ASCII) and (b) a type in itself (Unicode).

Question 26

ASCII meaning

Answer 26

American Standard Code for Information Interchange – a code that assigns numbers to letters, digits, etc.

Question 27

Allows Byte data types to be used to declare a variable that would hold a single character to initialize such variable or assign a **single quoted character**.

Answer 27

Byte for a Character Type **You need single quotes for a byte for it to initialize as a ASCII** (ASCII for 'f' is 102)

Question 28

To support characters that are not traditionally used in (US) English and do not work with compilers, the _ character format was created which includes **Latin-based** and **non-Latin-based languages**. The Char data type was created to support _ characters in Java.

Answer 28

Unicode **To initialize, assign the character variable in single quotes.**

Question 29

This data type is used for **logical** values and can only hold true or false values. It is a type returned by all relational operators such as =, >, and <.

Answer 29

Boolean

Question 30

These are based on primitive data types but with more functionality. For example, String is an abstract data type that can store letters, digits, and other characters such as a slash (/), comma (,), parentheses (()), semi-colon (;), dollar sign ($), and a hashtag (#).

Answer 30

Abstract Data Types

Question 31

an abstract data type that can store letters, digits, and other characters such as a slash (/), comma (,), parentheses (()), semi-colon (;), dollar sign ($), and a hashtag (#). This also provides methods for linking two (2) strings, searching for one string within another, and extracting a portion of a string.

Answer 31

String

Question 32

Performing calculations on a variable of the **string data type** is _, even if the data stored in it has digits

Answer 32

Not allowed

Question 33

a code that assigns numbers to letters, digits, etc.

Answer 33

American Standard Code for Information and Interchange or ASCII

Question 34

Long range

Answer 34

-2^63 to 2^63-1

Question 35

±1.4 × 10⁻⁴⁵ to ±3.4 × 10³⁸

Answer 35

Float

Question 36

±4.9 × 10⁻³²⁴ to ±1.8 × 10³⁰⁸

Answer 36

Double

Question 37

Char range

Answer 37

0 to 65,535

Question 38

What are the sizes of these: Byte Short Int Long

Answer 38

Byte: 8 Short: 16 Int: 32 Long: 64

Question 39

What are the sizes of these: Float Double Char Boolean

Answer 39

Float: 32 Double: 64 Char: 8 Boolean: 1

Question 40

Java uses **constants and variables** for **storing** and **manipulating** data in a program. The values of variables can be changed in a program, but the value of ___, **cannot**.

Answer 40

constants

Question 41

Unique names must be assigned to ________.

Answer 41

variables and constants

Question 42

If the name “digit” refers to an **area in memory** where a numeric **value is stored**, then “digit” is a _.

Answer 42

Variable

Question 43

_ is defined by the combination of an identifier, a type, and an optional initialization depending on the task to be performed.

Answer 43

Variable

Question 44

Regardless of the data type, each variable used in a program must be ___. The “digit” variable must be ____ with an **Int data type** since it refers to a memory storing an **integer value**.

Answer 44

Declared

Question 45

Just like identifiers, naming ___ must follow specific rules and conventions. The program will not compile if the programming language rules are not followed.

Answer 45

variables

Question 46

In general, here are the **rules** for naming **variables**.

Answer 46

1. The name of a variable must be **meaningful**, short, and without any embedded space or symbols. However, **underscores (_) can be used**. 2. Variable names must be **unique**. 3. A variable name must begin with a letter, a dollar sign, or an underscore. 3. **Keywords cannot be used** for variable names.

Question 47

For **Java**, here are the **variable naming conventions**.

Answer 47

1. Variable names should be **meaningful**. 2. The names must reflect the data that the variables contain. 3. Variable names are **nouns** and must **begin** with a **lowercase letter**. 4. If a variable name contains two or more words, begin each word with an **uppercase letter**. However, the first word will start with a lowercase letter.

Question 48

To declare more than one (1) variable of the same data type, a ___ separated list is used.

Answer 48

A comma (,)

Question 49

Variables cannot also be used without ______ them.

Answer 49

initializing

Question 50

Java assigns a **default value** to the ____ class variables **when creating an object or a class**.

Answer 50

primitive data types **class variables**

Question 51

The following displays the default initial values that are used to initialize the data members of a class. **Data Type** Byte: Short: Int: Long: Float: Double: Char: Boolean: Abstract:

Answer 51

Data Types and their **Default Initial Value** Byte: 0 Short: 0 Int: 0 Long: 0L Float: 0.0 Double: 0.0 Char: 'u0000' Boolean: false Abstract: Data Type Null

Question 52

0 or the default data types is **replaced** by the **actual value to be used**. The values are only automatically assigned to the data members of a class that are of the **primitive data types**. Java returns an error if the **variable** declared in a method is not ___.

Answer 52

initialized

Question 53

In Java, **variables** can be assigned with ____. The ____ to be assigned **must have the data type** of the **variable**.

Answer 53

Answer: **Constant** Values More info: Constants are permanent values (cannot be changed) (Not Constant) int age = 18; age = 19; System.out.println(age); // prints 19 (Constant) **final** int BIRTH_YEAR = 2007; BIRTH_YEAR = 2008; //error (u cant change a constant)

Question 54

_____ are the values that may be assigned to primitive- or string-type variables and constants.

Answer 54

Literals

Question 55

Boolean literals are ____ and cannot use numbers to represent them.

Answer 55

true or false

Question 56

___ are numeric data that can be represented as octal, hexadecimal, and binary literals. Octal is the number with a zero prefixed. Hexadecimal is the number prefixed with 0x. Binary Literal is the number that starts with 0B or 0b. An underscore (_) can be used to improve the readability of the numeric data.

Answer 56

Integer Literals

Question 57

(Integer Literals) ___ is the number with a **zero prefixed**.

Answer 57

Octal (Integer Literals)

Question 58

(Integer Literals) ____ is the number **Prefixed with 0x**.

Answer 58

**Hexadecimal** (Integer Literals)

Question 59

(Integer Literals) ___ is the number that starts with 0B or 0b.

Answer 59

Binary Literal (Integer Literals)

Question 60

(Integer Literals) An _ can be used to **improve the readability** of the numeric data.

Answer 60

underscore "_" (Integer Literals) Int aMillion = 1_000_000

Question 61

(Integer Literals) reminder that an underscore (_) at the start and end of a literal is _.

Answer 61

**Not allowed**

Question 62

____ are **numbers that have a decimal fraction**. A suffix letter F (lower or uppercase) to the number; otherwise, the compiler will flag about loss of precision.

Answer 62

Floating-point literals

Question 63

**Floating-point literals** are numbers that have a decimal fraction. A ____ is needed to the number; otherwise, the compiler will flag about loss of precision.

Answer 63

A **suffix letter F** (lower or uppercase)

Question 64

___ must also be enclosed in single quotes (‘,’). The **Unicode value** of the character is also **allowed**.

Answer 64

Character literals

Question 65

**Character literals** must also be enclosed in ___. The Unicode value of the character is also allowed.

Answer 65

single quotes (‘,’)

Question 66

(Character Literal) A _ can also be used to represent a character that can be typed in as a literal.

Answer 66

backslash "\\"

Question 67

_ are enclosed in double quotes (","). _ are included as literal as they can still be typed directly into the code, even though it is **not a primitive type**.

Answer 67

String literals

Question 68

string literals are enclosed in __. Strings are included as literal as they can still be typed directly into the code, even though it is not a primitive type.

Answer 68

double quotes (",")