Chapter 2 PDF Flashcards by Paul Hankewicz

What is the typical program structure

Input some data
Perform some processing on the data
Output the results

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Describe what could happen in each execution of the program

The data might be different

Instructions will be the same

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What do all Java Application programs consist of

All programs consist of at least one class

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What are identifiers used to name

Classes, variables and methods

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What are some identifier rules

Must start with a Java Letter
Can contain essentially any number of java letters and digits but no spaces
Case sensitive
Cannot be keywords or reserved words

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Is this identifier valid: taxRate

yes

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Is this identifier valid: char

No. Char is a keyword

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Is this identifier valid: intNumber

Yes, the keyword int is embedded but the identifier is not identical to a keyword

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Is this identifier valid: 2008Taxrate

No. The identifier starts with a digit

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Describe the statement in a program building block

Performs some action
Terminates with a semicolon;
Can span multiple lines

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Describe the block in the program building block

0,1, or more statements
begins and ends with curly braces {}
Can be used anywhere a statement is allowed

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What are white space characters. Describe them

Space, tab, and newline are white space characters.
At least one white space character is required between a keyword and identifier.
Any number of white space characters are permitted between identifiers, keywords, operators, and literals.

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What are comments used for

Comments explain the program to yourself and others.

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How do you comment a line

Begin with /* and end with */

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What is a requirement for all data

That you assign a name and a data type

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What is the purpose of a data type

How much memory to allocate
How to store the data
The types of operations you will perform on the data

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What are the eight primitive data types

byte
short
int
long
float
double
char
boolean

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How many values can a variable hold

Variables hold one value at a time, but the value can change as the program executes

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Describe the naming convention for variable names

First letter is lowercase

Embedded words begin with an uppercase letter

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What are boolean values used for

Boolean values are used for decision making or as flag variables

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Describe what putting an assignment operator does to variables

Value on the right of the operator is assigned to variable on the left

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What can the variable on the right be

A literal, another variable, or an expression

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What is a literal

Text representing a specific value

What is an expression

A valid combination of variables, operators and constants

Describe the literal int, short, byte

Optional initial sign (+ or -) followed by digits 0-9 in any combination

Describe the literal long

Optional initial sign (+ or -) followed by digits 0-9 in any combination, terminated with an L

What are interger literals that begin with 0 considered

They're considered to be octal values

What are integer literals that begin with 0x considered to be

They're considered to be hexadecimal values

Describe the float in floating point literals

Optional initial sign (+, or -) followed by a floating-point number in fixed or scientific format, terminated by a F

Describe the double in floating point literals

Optional initial sign (+ or -) followed by a floating point number in fixed or scientific format

what is a common error with integer or floating point literals

Commas, dollar signs, and percent signs (%) cannot be used in integer or floating point literals

What is a char

Any printable character enclosed in single quotes

What is rule 1 of assigning the values of other variables

Variable 1 needs to defined before this statement appears in the source code

What in rule 2 of assigning values of other variables

Variable 1 and variable 2 need to be compatible data types; in other words, the precision of variable 1 must be lower than or equal to that of variable2

What is a common error trap with variables

You need to declare a variable only once. After a variable is declared, its data type cannot be changed. After a variable is declared, its data type cannot be changed.

What is a string

String is a class not a basic data type.

What is a string variable

String variables are objects

What do String Concatenation Operator do

Combines String literals with other data types for printing

What is the common error trap with string literals

String literals must start and end on the same line

What is important to do with long strings to avoid common errors

Break long strings into shorter strings and use the concatenation operator

How do you include a special character in a string

You use an escape sequence

In what situation would you use a constant

Sometimes you know the value of a data item, and you know that its value will not change during program execution. Then you would define it as a constant.

Whats the convention for naming a constant

use all capital letters for constants and separate words with an underscore

What is an expression

Operators and operands that evaluate to a single value,

What happens to the single value (as a result of an expression)

The value is then assigned to a target

What is the requirement for a target (in relation to a single value as a result of an expression)

The target must be a variable or a constant and the value must be compatible with target's data type

When is operator precedence used

If more than one operator is used in an expression, the order of evaluation is determined using an operator precedence.

What is the order used in operator precedence

Expressions in parentheses are evaluated first | Multiplication, division, and modulus are performed before addition and subtraction

How would you evaluate an expression that has multiple arithmetic operators of the same precedence

They are evaluated left to right. An assignment is performed last and is performed right to left.

What happens when two integers are divided

The quotient is an integer | Any fractional part is truncated (discarded).

How do you get a remainder when you divide two intergers

Use the modulus operator with the same operands

Whats the result in floating point division( by 0) if the dividends not 0

The result is infinity

What is the result in floating point division( by 0) if the dividend and divisor are both 0

Nan (not a number)

What occurs when you perform calculations with operands of different data types

Lower precision operands are promoted to higher precision data types, then the operation is performed..

What is special about implicit type casting

Promotion is effective only for expression evaluation; not a permanent change