chapter 2

Question 1

constant

Answer 1

data type that cannot be changed when program is running

Question 2

literal constant

Answer 2

value taken literally at each use, e.g. numeric or boolean

Question 3

unnamed constant

Answer 3

no identifies associated with it

Question 4

variable

Answer 4

a named memory location
Used to store a value
Can hold only one value at a time
Its value can change

Question 5

Data type

Answer 5

A type of data that can be stored
How much memory an item occupies
What types of operations can be performed on data

Question 6

Primitive data type

Answer 6

a simple data type, 8 of these exist:

byte, short, int, long, float, double, char, booleon

Question 7

Reference types

Answer 7

more complex data type such as string

Question 8

Name variables

Answer 8

named memory locations used for legal class identifiers

Question 9

variable declaration

Answer 9

a statement that reserves a named memory location, this includes:
Data type
Identifier
Optional assignment operator and assigned value
Ending semicolon

Question 10

Assignment operator

Answer 10

The equal sign (=)

The value to the right is assigned to the variable on the left

Question 11

Initialization

Answer 11

An assignment made when declaring a variable

Question 12

Assignment

Answer 12

An assignment made after a variable is declared

Question 13

Associativity

Answer 13

The order in which operands are used with operators

Question 14

Whats the difference between declaring variables of the same type vs variables of a different type

Answer 14

variables of the same type may be declared on a single line whereas variables of different types must be declared on separate lines

Question 15

Named constant

Answer 15

• Should not change during program execution
• Has a data type, name, and value
• Has a data type preceded by the keyword final
• Can be assigned a value only once
• Conventionally is given identifiers using all uppercase letters

Question 16

Why use named constants

Answer 16

• Make programs easier to read and understand
• Enable you to change a value at one location within a program
• Reduce typographical errors
• Stand out as separate from variables
• Eliminates magic numbers

Question 17

Scope

Answer 17

• The area in which a data item is visible to a program, and in which you can refer to it using its simple identifier
• A variable or constant is in scope from the point it is declared
• Until the end of the block of code where the declaration lies

Question 18

What is a booleon

Answer 18

a true or false value

Question 19

what is a relational operator

Answer 19

an operator that compares two item

Question 20

what is a char data type

Answer 20

a data type which holds a single character

Question 21

what is a String

Answer 21

• built in class
• stores and manipulates character strings
• string constants are written between double quotes “”

Question 22

what is the issue of using a numeric scanner such as nextInt()

Answer 22

Keyboard buffer:

• This is a location in memory that stores all keystrokes, including enter
• As a result if the first scanner is an Integer scanner it may not pickup the enter keystroke from the buffer
• Then a scanner that registers enter may pick it up and register it as a keystroke and as a result not pick up any useful input
• To solve this you can add an extra nextLine() in order to retrieve and abandoned Enter key strokes following numeric or next() inputs

Question 23

dialog box

Answer 23

register user input i.e. entering something via keyboard or confirming something

Question 24

Input dialog box

Answer 24

asks question

provides text field for user response

Question 25

showinputdialog() method

Answer 25

-six overloaded versions -returns a string representing the user response One version requires: Parent component Message Title Type of dialog box

Question 26

Type-wrapper classes

Answer 26

- Primitive data types have corresponding classes contained in java, lang package - These include methods to process primitive values e.g. - Integer.parseInt() - Double.ParseDouble()

Question 27

What five arguments are needed to confirm a dialog box

Answer 27

- Parent component - Promp message - Title - Integer that indicated which option button to show - Integer that describes the kind of dialog box

Question 28

Standard Arithmetic operators

Answer 28

preform calulations with values in programs

Question 29

operand

Answer 29

a value used either side of an operator

Question 30

integer division

Answer 30

two integers are divided and the result is also an integer meaning any fractional part of the result is lost,

Question 31

What is operator precedence

Answer 31

rules for the order in which mathematical expressions are evaluated Multiplication, division, remainder (modulus), additon or subtraciton

Question 32

What are the rules of Type conversion

Answer 32

- Artithmetic variables or constants of same type return results of the same variable/constant type - Arithmetic operations with unlike operands will return a result of a unifying type which Java chooses, basically java converts the values to a common type in order for it to work

Question 33

Automatic Type conversion

Answer 33

the automatic conversion of nonconforming operands into a unifying operand type

Question 34

what is the order of establishing unifying types betweeen two variables from highest to lowest

Answer 34

Double Float Long Int

Question 35

what is type casting

Answer 35

forcing a value of one data type to be usef as value of another data type

Question 36

how do you use a cast operator

Answer 36

place desired value in parentheses | using a cast operator is an example of an explicit conversoin

Question 37

when do you not need to use a cast operator

Answer 37

when assigning a value to a higher unifying type e.g. Float to Double