calculating factorial using Java 8 IntStream?

Question

I am relatively new in Java 8 and lambda expressions as well as Stream, i can calculate factorial using for loop or recursion. But is there a way t

Answer 1

With LongStream.range() you can calculate factorial for number less 20. If you need calculate for larger number create stream with BigInteger:

 public BigInteger factorial(int number) {
    if (number < 20) {
        return BigInteger.valueOf(
                LongStream.range(1, number + 1).reduce((previous, current) -> previous * current).getAsLong()
        );
    } else {
        BigInteger result = factorial(19);
        return result.multiply(Stream.iterate(BigInteger.valueOf(20), i -> i.add(BigInteger.ONE)).limit(number - 19)
                .reduce((previous, current) -> previous.multiply(current)).get()
        );
    }
}