I have got this question multiple times! It is true that JodaTime could have been used. However, I wanted something far more simple with just a few additional convenience functions, and JodaTime seemed a little complex for the simple requirements. In fact I had considered using just Long instead of having the wrapper class Time. But I chose to keep the thin wrapper just in case we need to switch to a different internal format in the future, maybe JodaTime instead of Long. So for the time being this was simple, sufficient, while having the flexibility of extending it later.