Java Variables

The Java programming language has built-in "primitive" data types to support integer, floating-point, boolean, and character values. These primitive types hold numeric data that is understood directly, as opposed to object types defined by programmers. The type of every java variable must be defined explicitly.

The primitive data types java variable are:

boolean  either TRue or false
 
char    16-bit Unicode UTF-16 character (unsigned)
 
byte   8-bit integer (signed)
 
short   16-bit integer (signed)
 
int    32-bit integer (signed)
 
long   64-bit integer (signed)
 
float  32-bit floating-point (IEEE 754)
 
double  64-bit floating-point (IEEE 754)

For each primitive type there is also a corresponding object type, generally termed a "wrapper" class. For example, the class Integer is the wrapper class for int. In most contexts, the language automatically converts between primitive types and objects of the wrapper class if one type is used where the other is expected.

Java Variable access scope

Access scope of instance and class variables defines what objects can read and modify that variable.The four possible visibility modifiers are: public, protected, private, and no modifier.