First Java Program

In our first Java program, we are printing a “Hello World!!!” message.

Steps to run this Java code:

Here is the code to copy:

package com.techstackjournal;

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

Where to write this Java code?

• Text Editor
• Integrated Development Environment (IDE)

Though we can write the program in a Simple Text Editor, it is always better to use IDE, as it provides intellisense while to type code. Intellisense means, providing auto-complete options as type your program.

Writing Java Program in Text Editor

• Copy above program to a text editor
• Create a workspace folder like “D:\workspace”
• Save the file with name “App.java”
• Open Command Prompt
• Type cd d:\workspace to switch to the location of the file
• Compile your program using javac -d App.java command
• A class file with name App.class will be generated inside “com/techstackjournal” folders.
• To run this program type java com.techstackjournal.App

D:\workspace>javac App.java
D:\workspace>java com.techstackjournal.App
Hello World!!!

Writing Java Program in IDE

Choosing the IDE

• There are several IDEs available in the market
• Most used IDEs are Eclipse, IntelliJ IDEA, NetBeans
• NetBeans is free and opensource IDEs
• IntelliJ IDEA comes in Community and Commercial versions
• IntelliJ IDEA Community is free but only for pure Java related programming
• IntelliJ IDEA Commercial version supports other advanced features to work on web projects
• Eclipse is free and opensource
• Eclipse also comes in various versions and for various programming languages
• Throughout this course I’ll assume that you have downloaded Eclipse IDE for Enterprise Java Developers
• Eclipse downloads can be executed directly without installation

Create your Java program in Eclipse IDE

• Extract the eclipse zip file
• Get into eclipse folder and double click eclipse.exe
• Eclipse prompts for selecting workspace, give a relevant name here like JavaPracticeWorkspace
• Select Menu, File >> New >> Project
• Select, Java >> Java Project, click Next
• Enter the project name, FirstJavaProject, click Finish
• Click on Yes, to open associated perspective, that is Java
• Expand the newly created project
• Right click on src folder and select, New >> Class
• Remove the value for Package
• Enter “App” for Name
• Select the checkbox for “public static void main(String[] args)”
• Click on Finish button, you’ll see that partial code is written for you in App.java file
• Add the print statement inside main method, System.out.println("Hello World!!!");
• Press Ctrl+S to save the file
• Right click anywhere in the Java program and select, Run As >> Java Application
• The output will be printed in the “Console” view, just below the Java Editor