Can a judge finalize a divorce without notifying the defendant or getting signatures from the defendant or his attorney?

You have not provided enough information for an accurate/complete answer.  Are there children involved?  What about any marital property or debts?  Did he file a response when you initially filed for divorce?   There are some circumstances that allow for a judge to issue a final order on a divorce case without input from one of the parties.   Are/were you represented in this divorce?  You should definitely speak with an attorney.