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Introduction of Java

Java is object oriented programming language.

What is Java?

Java is object oriented programming language.

The Java programming language was developed by James Gosling from Sun in 1995.

Features of Java.

Simple
Portable
Object oriented
Platform Independent
Secured
Robust
Architecture neutral
Interpreted
High performance
Multi threaded
Distributed
Dynamic

What is OOPS?

OOPS is a programming approach which revolvs around the concept of "object".
Any entity in the system that can be defined as a set of properties and set of operations performed using entity's property set, is known as object.'

Encapsulation
Data hiding
Abstraction
Polymorphism
Inheritance

Variables

variables are the names of memory locations where we store data.
variable name is any combination of alphabet (a to z or A to Z), digit(0 to 9) and underscore (_).

Rules for naming variables in C#

First character must be alphabet or underscore(_).
no commas, blanks allowed
no special symbol other than (_) allowed
variables names are case sensitive we must create meaningful variables name in our programms.

Types of variables

local
global
static

local variable

local variable can declare and defineinside function of constructor block. It cannot access outside of function block.

global variable

global variable can declare out side of function block. global variable can acces any where in program, if it is public.

static variable

static variable can declare at the class level. No need to create an object to access static variable.

Keywords

Keywords are reserved words, whose meaning is already known to the compiler.

abstract	assert	boolean	break	byte	case
catch	char	class	continue	const	default
do	double	else	enum	exports	extends
final	finally	float	for	goto	if
implements	import	instanceof	int	interface	long
module	native	new	package	private	protected
public	requires	return	short	static	strictfp
super	switch	synchronized	this	throw	throws
transient	try	var	void	volatile	while

Comments

comments are used to clarify something about the program in plain languagqe.

There are two types of comments in C#.

Single line comment.
Multi line comment.

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