Java type annotations, multi-precision

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On Sunday, 9 February 2014 at 17:55:50 UTC, bearophile wrote:
> Francesco Cattoglio:
>
>> Wow, they are totally coping! :P
>
> What's interesting is not just that Java has type annotations, 
> but the details of this feature. That article show many details.
>
> Bye,
> bearophile

I don't think he mentioned it in the first article, but are these 
annotations checked at runtime or compile time? For example, 
@NonNegative.