Class X (ICSE) Data types

CLASS - X (ICSE)

COMPUTER  APPLICATION

Data Types

®      A type identifies a set of values (and their representation in memory) and a set of operations that transform these values into other values of that set.

®     Java is strongly typed language.

®     Types of data types

Ø  Primitive type (or Intrinsic Data Type)

Ø  Non-Primitive type(Reference/Object or Composite Data Type)

Primitive Data Types

®     Once a primitive data type has been declared its type can never change, although in most cases its value can change.

®     These eight primitive type can be put into four groups

Data type	Default value	Default size
boolean	false	1 bit
char	‘\u0000’	2 byte
byte	0	1 byte
short	0	2 byte
int	0	4 byte
long	0L	8 byte
float	0.0f	4 byte
double	0.0d	8 byte

Data Type	Range
boolean	Reserves 8 bits and only uses  bit
char	0(‘\u0000’) to 65,535(‘\uffff’)
byte	-128 to 127 ( -27 to 27-1)
short	(-215 to 215-1 )
int	(-231 to 231-1 )
long	(-263 to 263-1 )
float	-3.4E+38 to  +3.4E+38
double	-1.7E+308 to +1.7E+308

Non-primitive Data Type

®     A reference data type is used to refer to an object.

®     A reference variable is declare to be of specific and that type can never be change.

®      class, arrays, interface etc.

®     Eg: String, Scanner, Random, int[], String[] etc

®     Reference variables store addresses