Constaant, Variable and Datatype

Primitive Data Types   The eight primitive data types handle common types for integers, floating-point numbers, characters, and boolean values (true or false). They're called primitive because they're built into the system and are not actual objects, which makes them more efficient to use.   Integer Type There are four Java integer types, each with a different range of values. All are signed, which means they can hold either positive or negative numbers.

Table 3.1. Integer types Type Size Range byte 8 bits -128 to 127 short 16 bits -32,768 to 32,767 int 32 bits -2,147,483,648 to 2,147,483,647 long 64 bits -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807

Floating-point type: Floating-point numbers are used for numbers with a decimal part. There are two floating-point types: float (32 bits, single precision) and double (64 bits, double precision).

Char type: The char type is used for individual characters. Because Java uses the Unicode character set, the char type has 16 bits of precision, unsigned.