factorialLoop.java

public int factorial(int n)
{
  int total = 1;
  for(int i = 1; i < n; n++)
  {
     total *= i;
  }
  return total;
}

factorialRecursion.java

public int factorial(int n)
{
 if(n == 0 || n == 1)
 {
   return 1;
 }
  return factorial(n - 1) * n;
}

factorialStream.java

public int factorial(int n)
{
  return Intstream.rangeClosed(1, n).reduce(1, (a, b) -> a * b);
}