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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. This table shows all of the primitive data types:

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

Reference types are arrays, or names of classes or interfaces.

The variable declaration also implicitly sets the variable's scope, and you may optionally provide an initial value for the variable within its declaration. The value of a final variable may not change after it's initialized.

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