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The factorial of a non-negative integer n is the product of all positive integers less than or equal to n. It is denoted by n!.

For example, the factorial of __ is calculated as:

1__________ = 5 * 4 * 3 * 2 * 1 = 120

To implement the factorial function using recursion, we can follow these steps:

1. Define the base case: If n is 0 or 1, the factorial is 1.
2. Define the recursive case: If n is greater than 1, the factorial is calculated as n multiplied by the factorial of n - 1.
3. Use recursion to call the factorial function with n - 1 as the argument.
4. Return the result of n multiplied by the factorial of n - 1.

Let's fill in the blanks and complete the code:

1public class Factorial {
2  public static int factorial(int n) {
3    // Base case: If n is 0 or 1, return 1
4    if (n == 0 || n == 1) {
5      return 1;
6    }
7
8    // Recursive case: Return n * factorial(n - 1)
9    return n * factorial(n - 1);
10  }
11
12  public static void main(String[] args) {
13    // Example call to factorial for n = 5
14    int result = factorial(5);
15    System.out.println(result);
16  }
17}

The completed factorial function calculates the factorial of a given number n using recursion. Try running the example code to see the factorial of 5 being calculated and printed to the console.