Introduction to Java

Introduction to Java

i) Introducing Java Programming Language

ii) Java Environment Setup

iii) Java Program Structure
i) Introducing Java Programming Language

> Java Programming Language was developed at Sun Microsystems in 1991 (The first publicly available version of Java (Java 1.0) released in 1995, Now it is subsidiary of Oracle corporation.

> Java is an Object oriented Programming language, In Java every thing is object, java can be easily extended since it is based on Object model.

> Java is a Platform independent language, it can be compiled and Interpreted.

> Java is simple, easy to learn and implement.

> Java is Securable, using Java we can develop virus free and tamper free systems.
Usage of Java

> To develop Desktop Applications (ex: Acrobat Reader)

> To develop Web Applications

> To develop Enterprise Applications (Ex: Banking, Insurance Applications etc...)

> To develop Mobile Applications

> To develop Embedded Systems.

> Smart Cards

> Games software etc...
> Test Automation
Java Syntax Rules

> Java is a case sensitive language.

> First letter of Class name should be in Upper case.

> Method names should start with lower case letter.

> Java program file name should exactly match with class name.

> Java program execution starts from main method, which is mandatory in every Java program.

> Every statement/step should end with semi colon symbol.

> Code blocks enclosed with {}.
ii) Java Environment Setup


1) Download Java Software (JDK) and Install.

2) Set Environment Variable path (Path variable)

3) Download Eclipse IDE and extract
Download Java (JDK) Software from either or, and Install.

After Java Installation then you can get Java folder in C:\Program Files.
Set Environment Variable path (Path variable)


First take jdk bin directory path

Select MyComputer and right click
> Properties
> Advanced System Settings
> Environment Variables
> Select Path variable from system variables
> Edit
> Paste java bin directory path in variable value field
> OK
> Ok
> Close
1) write and execute a Java program using command promt.

2) write and execute a Java program using Eclipse IDE.
1) write and execute a Java program using command prompt.

In Computer Programming we have three steps.

i) Write Program

ii) Compile the Program

iii) Run / Execute the program.
Step 1: Write a Program

public class Sample {
public static void main (String [] args) {
System.out.println ("Hello Java World");
Step 2: Compile the Program

> Launch Command prompt
> Chang to Java program file directory.
> Type javac

* It creates Java class file
Step 3: Run / Execute the program.

Type java Sample

Then it display the Output on the Console.
2) write and execute a Java program using Eclipse IDE.

Eclipse IDE (Integrated Development Environment)

> Eclipse IDE is a platform to write and execute computer programs like Java, Perl, Python, Ruby, PHP etc...

> Eclipse IDE is open source.

> It provides Editor for writing programs, Syntax guidence, Context help, auto compilation etc...
Steps to Write and Execute a Java Program using Eclipse IDE :

> Launch Eclipse IDE

> Create Java Project

> Create Java Package

> Create Java Class

Write Java Program and Run.

Note: Eclipse IDE provides auto compilation facility.
A Sample Java Program

package abcd;
public class Smitha {
public static void main(String[] args) {
int a = 100;
System.out.println("Hello Java");


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