VARIABLE, DATA TYPE AND OPERATORS

Variables play an important role in computer programming because they enable programmers to write flexible programs. Rather than entering data directly into a program, a programmer can use variables to represent the data. Then, when the program is executed, the variables are replaced with real data. This makes it possible for the same program to process different sets of data. Every variable has a name, called the variable name, and a data type.

Type of Variable:
Local variable: Declared inside the Method.
Instance variable: Declared inside the class but out side the Method. It is not declared as Static. Static variable: Declared as static it can not be local.
Example: 
class A{ int data=10; // Instance variable static in m=3; //Static Variable void method(){ int n=7; // Local Variable } }
Data Type: Java support Primitive Data Type and Non-Primitive Data Type.

DATA TYPE	DEFAULT VALUE	DEFAULT SIZE
Boolean	false	1 bit
byte	0	1 byte
char	'\u0000'	2 byte
short	0	2 byte
int	0	4 byte
float	0.0f	4 byte
long	0L	8 byte
double	0.0d	8 byte
object	null	-

Operator Precedence:

Operators	Precedence
Postfix	expr++, expr--
Unary	++expr, --expr, +expr, -expr
Multiplicative	*, /, %
Additive	+, -
Shift	<<, >>, >>>
Relational	<<, <=, >=, instanceof
Equality	==, !=
Bitwise AND	&
Bitwise Exclusive OR	^
Bitwise Inclusive OR	|
Logic AND	&&
Logic OR	||
Ternary	?:
Assignment	=, +=, -+, *=, /=, %=, &=, ^=, <=, >>=, >>>=