Preventing questions from being answered years after the "correct" answer has been accepted

Question

Consider this SO question: Why is !true ? 'false' : 'true' returning 'true'?, even though the OP hasn't accepted a "correct" answer, most of the answers here are (pretty much) correct.

We get a new SO user who decides to answer the question anyways (granted he cannot see deleted answers) hopefully to get points.

How can we prevent redundant answers to be posted to a "simple" question? This would be especially useful to questions that are old and gets answered years later.

If there is a similar question, just feel free to close this.

Answer 1

We shouldn't prevent it. If a user is repeating answers that are already there, you can simply vote as you see fit. But just because a question is old and answered, that doesn't mean that a user can't come up with a great new answer to the question. Granted, that particular question will most likely not see that happen, but it should never be prevented.

Answer 2

Questions can be "protected" to address such concerns. The linked question was actually just marked as protected 10 minutes before you posted this. The text for that notice reads:

This question is protected to prevent "thanks!", "me too!", or spam answers by new users. To answer it, you must have earned at least 10 reputation on this site.

Answer 3

I'm not sure this should be stopped. For example, what if the new answer mentions that previous answers have been rendered obsolete by deprecation or the like, and provides an answer that is now the most correct? This isn't the sort of thing we should prevent.

That being said, users with >=500 rep can review answers from new users to old questions, and flag/downvote etc them if need be.

Answer 4

There is no way to automate something like this, since it doesn't follow a consistent set of criteria. Sometimes new answers to old questions by new users are helpful. Sometimes they're helpful even when another answer has already been accepted. Sometimes they're even better than the accepted answer. Sometimes they add relevant information about something that has changed since the question was posted, and this is more likely to happen if the question is old.

It's a case-by-case judgement call every time. Fortunately, there's a solution already in place that takes into account both the fact that there is a greater likelihood that an answer to an old question by a new user doesn't really need to be added, and the fact that this can only be determined by human judgement on a case-by-case basis. It's called the Late Answers review queue.

Answer 5

Consider this related tangent: What if it's an obscure, difficult question that only a few people might encounter, one which does not lend itself to "me too" answers. Those kinds of problems can be as tough as HeisenBugs. Maybe the question goes tumblweed ... If answers arrive so much later, they won't likely help the original poster, but maybe it will those that hit the same problem later.

As several have mentioned, time should only matter for stale technology. And adding to what Adi Inbar says, on finding a question with (now) obsolete methods - regardless the of answers - it could be helpful to chime in and explain why its outmoded and what to do instead. One real instance you'll see on Stackoverflow: android cursor-related functions, such as

c.getColumnIndex(Contacts.People.NAME)  

Contacts.People is deprecated, the better way to do it is:

{ enter *newer* code here }  // and the reason it's better is { ______ }