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Summary of Variables

When you declare a variable, you explicitly set the variable's name and data type. The Java programming language has two categories of data types: primitive and reference. A variable of primitive type contains a value. This table shows all of the primitive data types along with their sizes and formats:

Keyword	Description	Size/Format
(integers)
byte	Byte-length integer	8-bit two's complement
short	Short integer	16-bit two's complement
int	Integer	32-bit two's complement
long	Long integer	64-bit two's complement
(real numbers)
float	Single-precision floating point	32-bit IEEE 754
double	Double-precision floating point	64-bit IEEE 754
(other types)
char	A single character	16-bit Unicode character
boolean	A boolean value (true or false)	true or false

The location of a variable declaration implicitly sets the variable's scope, which determines what section of code may refer to the variable by its simple name. There are four categories of scope: member variable scope, local variable scope, parameter scope, and exception-handler parameter scope.

You can provide an initial value for a variable within its declaration by using the assignment operator (=).

You can declare a variable as final. The value of a final variable cannot change after it's been initialized.

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