Coding 6.5

name, so you need to choose names for the things

you will refer to in your program. 

Rules for naming identifiers:
An identifier is a sequence of characters that consists of letters, digits, underscores '_' and dollar sign $.
An identifier must start with a letter, an underscore or a dollar sign. It cannot start with a digit.
An identifier cannot be a reserved word.
An identifier cannot be true, false or null.
An identifier can be of any length.

Example of legal identifier:
$2, ComputerArea, area, radius

are for representing data of a certain type. To use

a variable, you declare it by telling the compiler its name as well as what type of data it represents. This variable declaration tells the compiler to allocate appropriate memory space for the variable based on its data type.

The syntax for declaring a variable is:
datatype variableName;

Example:
public class ComputeArea {
public static void main(String[] args) {
double radius;
double
double area;
radius = 20;
area = radius x radius x 3.14;
System.out.println (area);
}
}

In our ComputeArea program (as above), we declare radius and area to be double variables.
Other data types are: int, double, char, byte, short, long, float and boolean.

of the program, but a constant represents permanent data that

never changes.
In our ComputeArea program, we can declare 3.14 as a constant value and we can name it as PI because 3.14 represent Pi value.
Syntax for declaring a constant:
final datatype CONSTANTNAME = VALUE;
Example:
public class ComputeArea {
public static void main(String[] args) {
final double PI = 3.14;
double radius;
double area;
double area;
radius = 20;
area = radius x radius x PI;
System.out.println (area);

groups that share similar characteristics.

is simply a list of items. A flat taxonomy has

only top-level categories. In a flat taxonomy, the items are weighted equally, though on a website, it is common to put the most important item first on the list.

the interface of a website or intranet. It is often

represented as a tree or a flowchart.
Individual items within the hierarchy are arranged in order of importance or status. Moving up the hierarchy means expanding the category or concept. Moving down the hierarchy means refining the category or concept.

Categories can be linked to any other categories. And relationships

among items can have different meanings, including semantic ones.

taxonomies (sets of attributes), enabling the classification to be ordered

in multiple ways, rather than in a single, predetermined order (as in a strict hierarchy).

see what the end result will look like while the

interface or document is being created. Example: Microsoft Front Page; Adobe DreamWeaver

and do not permit an immediate way to see results

of the markup. Example: Notepad

related programs that are used to create and manage digital

content. Example: WordPress, Sharepoint, Joomla and etc.