How to update an Android widget every second ... to draw a clock with a seconds hand?

Question

I have been reading much from various sources on ways to update a widget that is using ImageView Canvas and Draw method to display a clock with a seconds hand.

It must be updated every second. What is the most efficient way to do this? Use a Service, the Alarm Manager, Handlers?

It can be done, e.g., the Android app "Arc Clock Widget".

Anyone with any ideas?

Thanks, Tom