Factorial is the product of all positive integers less than or equal to a given positive integer. For example, for the given number 5, the factorial is 120 (5*4*3*2*1). Let’s see how we can find the factorial of a number in Java.
Below is an example program that uses a recursive method to find the factorial of a given number. Recursion in Java is the process in which the method calls itself.
Example
public class Test {
public static void main(String[] args) {
System.out.println(factorial(5));
}
static int factorial(int num) {
if (num == 1) {
return 1;
} else
return (num * factorial(num - 1));
}
}
Output: 120
This code defines a static method named “factorial” that takes an integer argument and calculates the factorial of that number using recursion. The method checks if the input number is 1 and returns 1. Otherwise, it returns the input number multiplied by the factorial of input number -1.
Another way of finding the factorial of a number in Java would be using the for loop:
public class Test {
public static void main(String[] args) {
int n = 5, factorial = 1; // starts from 1
for (int i = 1; i <= n; i++) {
factorial = factorial * i;
}
System.out.println(factorial);
}
}
Output: 120
That’s it!