Example: Fibonacci Series using Recursion in Java

// Fibonacci Series using Recursion
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {

    // Recursive function to calculate the nth Fibonacci number
    public static int fibonacci(int n) {
        // Base cases
        if (n <= 1) {
            return n;
        }
        // Recursive step
        return fibonacci(n - 1) + fibonacci(n - 2);
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Step 1: Prompt user for the number of terms
        System.out.print("Enter the number of terms (n): ");
        int n = scanner.nextInt();

        // Step 2: Validate input
        if (n < 0) {
            System.out.println("Number of terms cannot be negative.");
        } else {
            // Step 3: Print the Fibonacci series
            System.out.println("Fibonacci Series up to " + n + " terms:");
            for (int i = 0; i < n; i++) {
                System.out.print(fibonacci(i) + " ");
            }
            System.out.println(); // For a new line at the end
        }

        scanner.close();
    }
}