"Hey, clean code! Just a heads-up — if someone enters zero or negative values, this code still returns surface area and volume, which may not be realistic. Adding input validation could make it more realistic.

Ah, I could have simplified my solution. Oh, well.

thanks! i simply forgot about it

It is not specified that haystack does not contains null's. In case of null String#valueOf will throw a NullPointerException. Pretty elegant solution though!