Topic 4218 min readStructured Tutorial

Hello World Example in Java

Quick Answer

Hello World Example explains starting with a Hello World program is a classic way to learn any programming language.

Learning Objectives

Explain the purpose of Hello World Example in a practical learning context.
Identify the main ideas, terms, and decisions involved in Hello World Example.
Apply Hello World Example in a simple real-world scenario or practice task.

Introduction

Starting with a Hello World program is a classic way to learn any programming language.

In this tutorial, you will learn how to write, compile, and run a simple Java program that prints 'Hello World' to the console.

The journey of a thousand miles begins with a single step.

What is a Hello World Program?

A Hello World program is the simplest program that outputs the message 'Hello World' to the screen.

It helps beginners understand the basic syntax and structure of a programming language.

Introduces the basic syntax of Java.
Demonstrates how to output text to the console.
Shows how to compile and run a Java program.

Writing Your First Java Program

Java programs are written in files with the .java extension.

The program must have a class with a main method where execution begins.

Create a file named Main.java.
Define a public class named Main.
Add the main method: public static void main(String[] args).
Use System.out.println() to print text.

Compiling and Running the Program

Java source code must be compiled into bytecode before running.

Use the Java compiler (javac) to compile the program.

Run the compiled bytecode using the Java Virtual Machine (java command).

Open a terminal or command prompt.
Navigate to the directory containing Main.java.
Compile with: javac Main.java
Run with: java Main

Practical Example

This example defines a class named Main with a main method that prints 'Hello World' to the console.

Examples

Simple Java Hello World Example

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

This example defines a class named Main with a main method that prints 'Hello World' to the console.

Best Practices

Always name your Java file the same as the public class inside it.
Use proper indentation for readability.
Include comments to explain your code when necessary.
Compile and run your program frequently to catch errors early.

Common Mistakes

Forgetting the main method signature exactly as public static void main(String[] args).
Mismatching the filename and public class name.
Missing semicolons at the end of statements.
Using incorrect capitalization (Java is case-sensitive).

Hands-on Exercise

Modify the Hello World Program

Change the program to print your name instead of 'Hello World'.

Expected output: Your name printed to the console.

Hint: Replace the string inside System.out.println().

Add Multiple Print Statements

Add two more lines to print additional messages after 'Hello World'.

Expected output: Three lines of text printed to the console.

Hint: Use multiple System.out.println() calls.

Interview Questions

What is the purpose of the main method in a Java program?

Interview

The main method is the entry point of a Java program where the execution starts.

Why must the Java filename match the public class name?

Interview

Java requires the filename to match the public class name to locate and load the class correctly during compilation and execution.

What is Hello World Example, and why is it useful?

Beginner

Starting with a Hello World program is a classic way to learn any programming language.