Java Primitive Data Types

Computers programs store data in variables. A data type or simply type is the type of data that can be stored in a variable. 

Java is a strongly typed language. That means that when we declare a variable in Java, we must always specify its type.

java data types are divided into two groups:

- Primitive types or Basic Types

- Non primitive types or Reference types

Primitive data types are built in to the programming language. This data types are predefined by the language.

Reference data types are the programmer-defined classes and the types defined by classes in the Java API.

There are eight primitive data types in Java:

Data Type	Description	Size (Bytes)	Range	Default Value	Wrapper Class
byte	Signed integer	1	-128 to 127	0	Byte
short	Signed integer	2	-32.768 to 32.767	0	Short
int	Signed integer	4	-2147483648 to 2147483647	0	Integer
long	Signed integer	8	-9223372036854775808 to 9223372036854775807	0	Long
float	Single-precision floating point	4	± 3.4x10-38 to ± 3.4x1038	0.0	Float
double	Double-precision floating point	8	± 1.8x10-308 to ± 1.8x10308	0.0	Double
char	Unicode character	2	\u0000 to \uFFFF	\u0000	Character
boolean	Logical data type	-	true - false	false	Boolean

INTEGER DATA TYPES

There are four integer data types: byte, short, int, long.

For example:

int a = 3;

byte n1, n2;

short x = -1;

FLOATING POINT DATA TYPES

There are two floating point data types: float, double.

For example:

float weight;

double price;

double amount = 1.7E4;  // 1.7 * 10⁴

double z = .123;   //0.123

CHARACTER DATA TYPE

The character data type is represented by the char type.

The char type is used to store a Unicode character in the range \u0000 to \uFFFF.

The first 127 Unicode characters correspond with the ASCII code.

For example:

char ch;

char ch1 = 'z';

char ch2 = '\u0061'; // unicode for ‘a’

BOOLEAN DATA TYPE

The following declares two boolean variables:

boolean first = true;

boolean last = false;