Calculate factorial of a number in Java using recursion

Carvia Tech | May 18, 2019 | 1 min read | 26 views | Java Coding Challenges

Factorial of a number is calculated using below formula:

factorial (n) = n x (n-1) x (n-2) ... 1

the factorial of a number is calculated by formula number * (number -1) till zero and since the value of factorial zero is 1, it acts as a base case in the recursive version of the factorial method.

Recusive function to calculate factorial

public class Factorial {
    public int factorial(int n) {
        if (n == 1)
            return 1;
        else {
            return n * factorial(n - 1);
        }
    }
}

Iterative approach for factorial

public int fact(int number) {
    int result = 1;
    while (number != 0) {
        result = result * number;
        number--;
    }
    return result;
}

Here we are using int to hold the result of multiplication, which can quickly overflow due to maximum limit an integer can hold. We can improve the above two programs to use BigInteger as discussed in the below article:

How will you calculate factorial of a large number in Java