What usually happens when you violate probation of a year by not appearing to a court that you were not notified of?

A warrant can be issued for your arrest for violation of probation. Then a Judge decides whether to put you in jail or give you another chance.

On a general bases does the hearing take a long time?

Not in my area, no.

Why is it that a notice of court date wouldn't have been sent but the warrant was?

I have no idea - my feeling is that it WAS sent and you just didn't get it and that will be the PO's testimony. If it didn't come back to the office that did the mailing it is legally presumed to have been received.

Did the probation office have the correct mailing address for you? If you moved and did not properly notify the PO, then you never got the notice but somehow got the warrant.

Hearings for VOP's usually take less than 15 minutes. They usually take place once you have been in custody for several days or a week or more. They want to make sure you will attend the hearing hence the waiting in jail for the hearing.

Get an attorney to help you on this matter.