How long does it take to learn programming from scratch with no prior knowledge and using only free online resources (e.g. Codecademy)?

depends upon who you are, ( diligently working at it an hour a day) and what your metric of learning is

are you looking to be as good as a college grad?

are you looking to be capable to write a “sort routine from scratch”?

Assuming you’re capable of sorting things on your own, - trust me you will get stuck and not know

what to do and codeacademy has no hotline to help you out.

I’d say 3 yrs of diligent work to be capable of writing that sort routine, file I/O and perhaps and app.

in java.