Java Tutorial For Beginners: Part 3.

Problem: Java Program To Find Factorial Of A Number

import java.util.Scanner;

class Factorial {

public static void main(String args[]) {

int n, c, fact = 1;

System.out.print("Enter An Integer To Calculate It's Factorial: ");

Scanner s = new Scanner(System.in);

n = s.nextInt();

if ( n < 0 )

System.out.println("Number Must Be Non-negative.");

else

{

for ( c = 1 ; c <= n ; c++ )

fact = fact*c;

System.out.println("Factorial Of "+n+" Is = "+fact);

s.close();

}}}

Problem: Java Program To Find Factorial Of A Number Using Recursion

import java.util.*;

public class FactorialRecursion {

public static void main(String args[]) {

int num, factorial = 1;

Scanner s = new Scanner(System.in);

System.out.print("Enter An Integer To Calculate It's Factorial: ");

num = s.nextInt();

if ( num < 0 )

System.out.println("Number Must Be Non-negative.");

else {

factorial = getfactorial(num);

System.out.println(num + "! = " + factorial);

s.close();

}}

public static int getfactorial(int num) { 

if (num <= 1)

return 1;

return num * getfactorial(num-1);

}}

Problem: Java Program For Calculating Factorial Of Large Numbers

import java.util.*;

import java.math.BigInteger;

class FacorialOfBigNuumber {

public static void main(String args[]) {

int n=0, c;

BigInteger inc = new BigInteger("1");

BigInteger fact = new BigInteger("1");

Scanner input = new Scanner(System.in);

if ( n < 0 )

System.out.println("Number Must Be Non-negative.");

else {

System.out.print("Enter An Integer: ");

n = input.nextInt();

for (c = 1; c <= n; c++) {

fact = fact.multiply(inc);

inc = inc.add(BigInteger.ONE);

}

System.out.println(n + "! = " + fact);

input.close();

}}}