Basic Syntax

        
          // Package declaration (optional)
package com.example;

// Import statements
import java.util.Scanner;
import java.util.List;
import java.util.ArrayList;

// Class declaration
public class HelloWorld {
    // Main method - entry point
    public static void main(String[] args) {
        // Print to console
        System.out.println("Hello, World!");

        // Variables
        int age = 25;
        double price = 19.99;
        String name = "John";
        boolean isStudent = true;

        // Constants (final keyword)
        final double PI = 3.14159;

        // Arrays
        int[] numbers = {1, 2, 3, 4, 5};
        String[] names = new String[3];
        names[0] = "Alice";

        // Enhanced for loop
        for (int number : numbers) {
            System.out.println(number);
        }

        // Command line arguments
        if (args.length > 0) {
            System.out.println("Arguments: " + args[0]);
        }
    }
}

// Another class in same file
class Calculator {
    // Static method
    public static int add(int a, int b) {
        return a + b;
    }

    // Instance method
    public int multiply(int a, int b) {
        return a * b;
    }
}