Writing Your First Java Program: "Hello, World!"

Introduction:

Java is a widely used, versatile programming language designed for portability, performance, and maintainability. Its "write once, run anywhere" philosophy allows code to be executed on any device that supports Java, making it a popular choice for many applications, from web servers to mobile apps. In this article, we will create a simple Java program that prints "Hello, World!" to the console. This traditional first program will introduce you to the basic structure of a Java application.

Writing the first Hello World Program:

1. Create a Project Directory

   First, create a directory for your project. This helps keep your files organized. For example:

   mkdir HelloWorld
   cd HelloWorld

2. Write the Code

   Create a new file named HelloWorld.java using your IDE or text editor. In this file, write the following code:
   
   
   public class HelloWorld {
       public static void main(String[] args) {
           System.out.println("Hello, World!");
       }
   }

   
   
   Let's break down this code: Line-by-Line Explanation

   public class HelloWorld {

   public: An access modifier indicating that this class is accessible by any other class.
   class: A keyword used to declare a class in Java.
   HelloWorld: The name of the class. It must match the filename (HelloWorld.java).

   public static void main(String[] args){

   public: This method is accessible from anywhere.
   static: This method can be called without creating an instance of the class.
   void: This method does not return any value.
   main: The name of the method. This is the entry point of any Java application.
   String[] args: An array of strings passed as command-line arguments.

   System.out.println("Hello, World!");

   System: A class in the java.lang package.
   out: A static member of the System class, representing the standard output stream.
   println(): A method of PrintStream class (referenced by System.out) that prints the argument passed to it and then terminates the line.

   }:	//Closes the main method.

   }:	//Closes the HelloWorld class.

3. Compile the Code

   Java is a compiled language, meaning you need to compile your source code into bytecode that the Java Virtual Machine (JVM) can execute. Use the following command to compile your program:

   javac HelloWorld.java

   This command generates a file named HelloWorld.class containing the bytecode.
   
   

4. Run the Program

   Execute the compiled bytecode with the JVM using the following command:

   java HelloWorld

   You should see the output:

   Hello, World!