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You'll see how a simple Java program is structured and what its main parts are.

Here is an example of a Java program:

Main.java


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package com.example;

public class Main {

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

This may look a bit overwhelming at first, but don't worry — we'll break it down step by step.

At the highest level, every Java program is written inside a class. A class is simply a container that holds your code. In this example, the class is called Main.

Inside the class, you have the main method:

public static void main(String[] args)

This is the starting point of every Java program. When you run your code, Java always begins execution from this method.

Inside the main method, you have the actual instruction:

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

This line tells Java to display text on the screen. In this case, it prints:

Hello, world!

You will also notice curly braces:

{ }

These are used to group code together. Everything inside a pair of curly braces belongs to the same block.

Finally, you'll see a semicolon at the end of most statements:

A semicolon marks the end of an instruction. You can think of it like a period in a sentence — it tells Java that the command is finished.

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Section 1. Chapter 3

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Structure of a Java Program