Java — How Java Compiles & Runs & Source File Structure

// 1. Package statement (conceptual for tutorial demonstration)
// package com.ourcompiler.demo;

// 2. Import statements from standard class library
import java.util.Date;
import java.time.LocalDate;

// 3. Primary public class matching filename: SourceStructureDemo.java
public class Main {
    
    // 4. Class-level constants & fields
    public static final String COURSE_NAME = "Java Masterclass 2026";

    // 5. Main execution entry point
    public static void main(String[] args) {
        System.out.println("Course Title   : " + COURSE_NAME);
        System.out.println("System Date    : " + new Date());
        System.out.println("Current Year   : " + LocalDate.now().getYear());
        
        // Calling a helper method
        displaySystemArchitecture();
    }

    // 6. Custom member method
    public static void displaySystemArchitecture() {
        System.out.println("Architecture   : 2-Step JIT Bytecode Compilation Model");
        System.out.println("Status         : Fully Compliant with Java 21 LTS Standard");
    }
}

Course Title   : Java Masterclass 2026
System Date    : Sun Aug 16 13:45:00 IST 2026
Current Year   : 2026
Architecture   : 2-Step JIT Bytecode Compilation Model
Status         : Fully Compliant with Java 21 LTS Standard

// Multi-class demonstration in a single compilation unit
class DatabaseConnector {
    void connect() {
        System.out.println("[DatabaseConnector] Connected to PostgreSQL Database.");
    }
}

class SecurityGuard {
    boolean authenticate(String token) {
        return token.equals("AUTH_SECRET_2026");
    }
}

public class Main {
    public static void main(String[] args) {
        System.out.println("--- Starting Enterprise Service Bootstrapping ---");
        
        SecurityGuard guard = new SecurityGuard();
        boolean isAuth = guard.authenticate("AUTH_SECRET_2026");
        System.out.println("Authentication Status: " + (isAuth ? "GRANTED" : "DENIED"));

        if (isAuth) {
            DatabaseConnector db = new DatabaseConnector();
            db.connect();
            System.out.println("System Ready for Production Traffic.");
        }
    }
}