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Java Hello World Program Explained for Beginners | First Java Program Guid


Learn how to write and run your first Java program with a simple HelloWorld example. Step-by-step explanation of code structure, compilation, JVM execution, and beginner tips.

Your First Program: HelloWorld.java

In Java, every piece of code must live inside a class. Here is what the code looks like:

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

Breaking Down the Code

Don’t worry if this looks like a secret code at first. Here is what each part actually does:

  • public class HelloWorld: This defines the “bucket” for your code. In Java, the filename must match the class name (so this file must be saved as HelloWorld.java).
  • public static void main(String[] args): This is the entry point. It’s the door the computer walks through to start running your program. Without this specific line, your program won’t run.
  • System.out.println: This is the command that tells the computer to “print” or display text on the screen.
  • The Semicolon (;): Think of this as a period at the end of a sentence. It tells Java the instruction is finished.

How Java Works

Unlike some languages that run directly, Java uses a two-step process to ensure it can run on any device (Windows, Mac, or Linux).

  1. Compile: You run your code through a compiler (javac), which turns your readable text into “Bytecode.”
  2. Run: The Java Virtual Machine (JVM) reads that bytecode and executes it on your specific computer.

3 Steps to Run It

If you have the Java Development Kit (JDK) installed, you can try this right now:

  1. Save: Copy the code above into a text editor (like Notepad or TextEdit) and save it as HelloWorld.java.
  2. Compile: Open your terminal or command prompt and type: javac HelloWorld.java
  3. Execute: Type: java HelloWorld

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