What is DataType and Variable in java ?

>In this post, we will learn about the  variable and java data types.
>Variable is a name of memory location.
>There are three types of variables:
 local, instance and static.
>There are two types of datatypes in java,
   primitive and non-primitive.

Variable:

Variable is name of reserved area  allocated in memory. int age=20;  //Here age is a variable

Types of Variable:

There are three types of variables in java

> local variable
> instance variable
> static variable

Local Variable: A variable that is declared inside the method is called local variable.

Instance Variable: A variable that is declared inside the class but outside the method is called instance  variable .It is not declared as static.

Static variable: A variable that is declared as static is called static variable.It cannot be local.

Example to understand the types of variables:

class Test{
int data=50; //instance variable
static int m=100; //static variable
void method(){
int a=90; //local variable
  }
}


Data Types in Java:

In java, there are two types of data types

>1 Primitive data types
>2 Non-primitive data types

Primitive data types:

Boolean---------------->boolean
Numeric: It has 3 types
>Character------------>char
>Integer-------------->byte, short, int long
>Floating-point------->float,double


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          0                    8 byte
float          0.0                 4 byte
double       0.0                8 byte


Why char uses 2 byte in java and what is \u0000  ?

Because java uses unicode system rather than ASCII code  system. \u0000 is the lowest range of unicode  system.

To get detail about Unicode System see  Unicode System post.