Getting Started - Java - page 15

Variables
Every variable in a Java program must be declared before it is used. When you declare
a variable, you are telling the compiler—and, ultimately, the computer—what kind of
data you will be storing in the variable. For example, the following are two declara-
tions that might occur in a Java program:

declare

int numberOfBeans;
double oneWeight, totalWeight;

The first declares the variable numberOfBeans so that it can hold a value of type int ,
that is, a whole number. The name int is an abbreviation for “integer.” The type int is
the default type for whole numbers. The second definition declares oneWeight and
totalWeight to be variables of type double , which is the default type for numbers with
a decimal point (known as floating-point numbers ). As illustrated here, when there is
more than one variable in a declaration, the variables are separated by commas. Also,
note that each declaration ends with a semicolon.
Every variable must be declared before it is used. A variable may be declared any-
place, so long as it is declared before it is used. Of course, variables should always be
declared in a location that makes the program easier to read. Typically variables are
declared either just before they are used or at the start of a block (indicated by an
opening brace { ). Any legal identifier, other than a keyword, may be used for a vari-
able name.

floating-point
number

Variable Declarations
In Java, a variable must be declared before it is used. Variables are declared as follows:
SYNTAX
Type Variable_1 , Variable_2 ,. . .;

EXAMPLES
int count, numberOfDragons, numberOfTrolls;
char answer;
double speed, distance;

Syntactic Variables
Remember that when you see something such as Type , Variable_1 , or Variable_2 , these
words do not literally appear in your Java code. They are syntactic variables , which means
they are replaced by something of the category that they describe. For example, Type can
be replaced by int , double , char , or any other type name. Variable_1 and Variable_2 can
each be replaced by any variable name.