Structure of a Java Program

// Quick Answer
  • Every Java program is written inside a class.
  • The program execution starts from the main method.
  • Java code is case-sensitive and structured.
  • Statements end with semicolons.
  • Proper structure is required for successful execution.

What is the structure of a Java program?

:contentReference[oaicite:0]{index=0} programs follow a strict structure. Every program must contain a class, a main method, and executable statements inside it.

Basic structure

A simple Java program looks like this:

Main.java
public class Main {

    public static void main(String[] args) {

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

    }
}

Explanation of components

  • Class — Java code is written inside a class.
  • main method — Entry point of execution.
  • System.out.println() — Prints output on screen.
  • Braces { } — Define blocks of code.
  • Semicolon ; — Ends each statement.

How execution works

When a Java program runs, the JVM looks for the main() method and starts executing line by line from there.

💡 Important

If the main method is missing, the Java program will not run.

Summary

The structure of a Java program is simple but strict. Everything must be inside a class, and execution always begins from the main method.