Java Program to Find Factorial of Given Number

import java.util.Scanner;

class findFactorial {
  public static void main(String args[]) {

    int N, counter, factorial = 1;

    System.out.print("Enter An Integer: ");
    Scanner in = new Scanner(System.in);
    N = in.nextInt();

    if (N < 0){
      System.out.println("nNumber must be Non-negative.");
    }
    else {
      for (counter = 1; counter <= N; counter++)
        factorial = factorial * counter;
      System.out.println("nFactorial of " + N + " is = " + factorial);
    }
  }
}

Enter An Integer: 6
Factorial of 6 is = 720

import java.util.Scanner;
import java.math.BigInteger;

class BigFactorial {
  public static void main(String args[]) {
    
    int N, counter;

    BigInteger increment = new BigInteger("1");
    BigInteger fact = new BigInteger("1");

    Scanner input = new Scanner(System.in);
    System.out.println("Input an integer: ");
    N = input.nextInt();


    if (N > 0) {
      for (counter = 1; counter <= N; counter++) {
        fact = fact.multiply(increment);
        increment = increment.add(BigInteger.ONE);
      }
      System.out.println(N + "! = " + fact);
    }
    else{
      System.out.println("nNumber must be Non-negative.");
    }
  }
}

Enter An Integer: 6
Factorial of 6 is = 720