Example: Prime Number Checker in Java

// Prime Number Checker
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    public static void main(String[] args) {
        // Step 1: Create a Scanner object to read user input
        Scanner scanner = new Scanner(System.in);

        // Step 2: Prompt the user to enter a number
        System.out.print("Enter a number: ");
        int number = scanner.nextInt();

        // Step 3: Initialize a boolean flag to track primality
        boolean isPrime = true;

        // Step 4: Handle special cases for numbers less than or equal to 1
        if (number <= 1) {
            isPrime = false;
        } else {
            // Step 5: Iterate from 2 up to the square root of the number
            // If any number in this range divides 'number' evenly, it's not prime
            for (int i = 2; i * i <= number; i++) {
                if (number % i == 0) {
                    isPrime = false;
                    break; // No need to check further, it's not prime
                }
            }
        }

        // Step 6: Print the result based on the isPrime flag
        if (isPrime) {
            System.out.println(number + " is a prime number.");
        } else {
            System.out.println(number + " is not a prime number.");
        }

        // Step 7: Close the scanner to prevent resource leaks
        scanner.close();
    }
}