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INTRODUCTION OF JAVA

Java is an object-oriented programming language developed by Sun Microsystems, a company best known for its high-end Unix workstations. Modeled after C++, the Java language was designed to be small, simple, and portable across platforms and operating systems.

A Java program is a collection of classes definitions plus one special class, called the "driver".

Every class is a descendant of the class Object.

The current version of Java is 1.7 also known as Java 7.0. The main components of java language are compiler java virtual machine and Java class libraries.

HISTORY OF JAVA

Sun (Gosling) creates Oak, a language for embedded systems.<.p>

Specification of virtual machine yields platform independence.

Internet access promotes multi-platform languages.

Oak becomes Java.

World goes crazy.

Warning: Java is changing.

Core JAVA VERSION HISTORY

There are many java versions that has been released. Current stable release of Java is Java SE 8.

1) JDK Alpha and Beta (1995)

2) JDK 1.0 (23rd Jan, 1996)

3) JDK 1.1 (19th Feb, 1997)

4) J2SE 1.2 (8th Dec, 1998)

5) J2SE 1.3 (8th May, 2000)

6) J2SE 1.4 (6th Feb, 2002)

7) J2SE 5.0 (30th Sep, 2004)

8) Java SE 6 (11th Dec, 2006)

9) Java SE 7 (28th July, 2011)

10) Java SE 8 (18th March, 2014)

EDITOR USED FOR DEVELOPMENT OF JAVA APPLICATION / PROGRAM /PROJECT.

1) Notepad.

1) JCreator.

1) NetBeans.

1) Eclipse.


SYNTAX OF JAVA PROGRAM

Access_Specifier class class-Name
{
  public static void main(String[] args) 
  {
    System.out.println("Hello World!");
  }
}

NOTE:- Here

The Acess_ Specifier may be public, private, protected or default. It depends type of class.

Class is a keyword which is used to create a class.

Class _Name is user defined type which is not include in class name keywords or reserve words.

WHAT IS MEANT BY OBJECTS IN JAVA

An object is the piece of code which combines in a single unit both data and the process that operate on that data .

i.e- In object oriented language like java , the data and functions are bundled together as a self combined unit called an object

AN object is a single or smallest or basic runtime entity that has some properties and behavior associated with it.

USE OF OBJECT IN OOPS (JAVA)

a) They correspond to the real life entity

b) They provide interaction with the real world .

c) They provide practical approach for implementation

NOTE:- Every object have STATE, BEHAVIOUR and IDENTITY

STATES OF AN OBJECT

States is also called attributes of objects

States or attributes is the built in characteristics of object

for ex- A laptop has the attribute size , color , brand and model etc.

BEHAVIOUR OF AN OBJECT

Behavior is the predefined function like a laptop has behavior sound , picture quality etc

IDENTITY OF AN OBJECT

Identity is the property of object through which we can uniquely identify the object .

for ex- The laptop does not become a PC

An object consists of TWO things

1) Data member and,

2) Member function or Methods

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