Java - Fallo con Factorial Urgente

package Exercicis;

import java.util.Random;

public class Ex6 {

	public static void main(String[] args) {

		Ex6 programa = new Ex6();

		programa.inici();

	}

	public void inici() {

		int[] enters = new int[8];

		generarArray(enters);

		mostraFactorial(enters);

	}

	public void generarArray(int[] a) {

		System.out.print("Array aleatori: ");

		for (int i = 0; i < 8; i++) {

			Random aleatori = new Random();

			double valorAleatori = aleatori.nextDouble() * 10;

			int arrodonir = (int) Math.round(valorAleatori);

			while (arrodonir == 0) {

				valorAleatori = aleatori.nextDouble() * 10;

				arrodonir = (int) Math.round(valorAleatori);

			}

			a[i] = arrodonir;

			System.out.print(a[i] + " ");

			a[i] = factorial(i);

	//		int[] factorial = new int[8];

	//	factorial[i] = factorial(i);

		}

			System.out.println("");

	}

	public static int factorial(int num) {

		int factorial = 0;

		if (num == 0)

			factorial = 1;

		else if (num < 0)

			System.out.println("No existeix.");

		else if (num > 0)

			for (factorial = num; num > 1; num--)

				factorial *= (num - 1);

		return factorial;

	}

	public static void mostraFactorial(int[] a) {

		System.out.print("Factorials: ");

		for (int i = 0; i < a.length; i++)

			System.out.print(a[i] + " ");

		System.out.println("");

	}

}