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Introduction

[a] JAVA a programming language


JAVA is a programming language. A Desktop or web application can be developed in JAVA.
Like any other programming language such as C, C++, Pascal, COBOL etc, Java has capability to implement any algorithm using variables and control statements.
In general a language needs to store information and implement a flow of conditional statements in order to perform a task. Variables are used to store the information and control statements like if, while, and for are used to implement algorithms. Each computer language has capability to interact with standard input and output devices, interact with file system, and interact with database etc.
If you know any programming language you already know most of the JAVA.

[b] JAVA Learning Myths

Most common myth about JAVA is that you must learn C or C++ language before even thinking about JAVA. Truth is just opposite, JAVA can be learnt without knowing any other programming language.

[c] History

Java is an object oriented programming language created by James Gosling from Sun Microsystems (Sun) in 1991. The first publicly available version of Java (Java 1.0) was released in 1995. Sun Microsystems was acquired by the Oracle Corporation in 2010.
With the development of technology new enhanced versions of Java have been released over the period of time.
From the Java programming language the Java platform evolved. The Java platform is usually associated with the Java virtual machine and the Java core libraries.

[d] Open Source

In 2006 Sun started to make Java available under the GNU General Public License (GPL). Oracle continues this project called OpenJDK.

[e] JAVA is Object Oriented

A Money Oriented person always thinks in terms of money, likewise JAVA is Object Oriented so always thinks in terms of Object. What object will do, is decided by a Class.
A Class defines the role and responsibility of an Object and defines its structure. Each class is the expert class.
An Expert does not overlap the services of other Expert, similarly an Expert Class does not overlap services of any other expert Class.
For every program you have to create a Class in Java. A program of sum of two numbers, Fibonacci series, sending Emails, sending SMSs is nothing but a Class in Java.

For example Math class is the expert of mathematical operations like max, min, exponential and square root, SMS class is the expert of sms services like send message and receive message, Email class is expert of email services, Account class is expert of account services like deposit and withdrawal.

Expert classes bring modularity and reusability in the system.

An expert class will be developed once and can be reused in multiple applications. For example Email and SMS classes are developed once and reused in multiple applications like Banking, Insurance, and Ticket Reservation application.



Figure: Modularity and Reusability of Expert Classes


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