How to use method for calculating factorial of a number in Java

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Problem Description

How to use method for calculating factorial of a number?

Solution

This example shows the way of using method for calculating Factorial of 9(nine) numbers.

public class MainClass {
   public static void main(String args[]) {
      for (int counter = 0; counter <= 10; counter++) {
         System.out.printf("%d! = %d\n", counter, factorial(counter));
      }
   }
   public static long factorial(long number) {
      if (number <= 1) return 1;
      else return number * factorial(number - 1);
   }
}

Result

The above code sample will produce the following result.

0! = 1
1! = 1
2! = 2
3! = 6
4! = 24
5! = 120
6! = 720
7! = 5040
8! = 40320
9! = 362880
10! = 3628800

The following is an another example of factorial

public class NumberFactorial {
   public static void main(String[] args) {
      int number = 5;
      int factorial = number;
      
      for(int i = (number - 1); i > 1; i--) {
         factorial = factorial * i;
      } 
      System.out.println("Factorial of 5 is " + factorial);
   }
}

The above code sample will produce the following result.

Factorial of 5 is 120