Not at all. It is more black and white, where most people falls in one shade of gray or another, and there is a 50-50 mix too.
A detailed Myers-Briggs test will give you what percent are you on. See http://en.wikipedia.org/wiki/Myers-Briggs_Type_Indicator, in particular "The test is scored by evaluating each answer in terms of what it reveals about the taker. Each question is relevant to one of the following cognitive learning styles. Each is not a polar opposite, but a gradual continuum."
I do believe though that there is no correlation with your quality as programmer. Being a good quality programmer is more related to the ability to sustain and simulate detailed abstract models in your mind... but that is a blog post on its own.
No, it's a continuum. Most people need both; introverts go stir crazy after a while and have to interact with people, and extroverts get tired and want a moment to themselves.
It's more what drains you faster, what can you handle an excess of more easily. I consider myself an introvert because I very quickly get tired of people and shut down; it takes a day or two of being on my own (or otherwise not interacting socially with others) before I begin to crave it.
Or put another way, as an introvert, solitude may recharge me, but once recharged I need to expend that energy (else I get depressed and antsy). When actually in social settings, I may at first blow through a good chunk of that energy by being amiable and outgoing, once I start getting low I tend to be judicious in how I expend it, as it drains at different rates (crushed in a crowd it drains very fast. Alone with a single friend, talking, eating, gaming, whatever, it drains very slowly).
Few if any people can handle days on end of either solitude or company without tiring of it and needing the other at least briefly.
I think the idea is more that following (2), introverts lose energy whilst extroverts gain energy. (1) doesn't really come into it. You are probably extroverted.
But no it isn't necessarily a dichotomy, rather a rough label of how someone responds to social situations. Their actual character will be much more complex :)
A detailed Myers-Briggs test will give you what percent are you on. See http://en.wikipedia.org/wiki/Myers-Briggs_Type_Indicator, in particular "The test is scored by evaluating each answer in terms of what it reveals about the taker. Each question is relevant to one of the following cognitive learning styles. Each is not a polar opposite, but a gradual continuum."
I do believe though that there is no correlation with your quality as programmer. Being a good quality programmer is more related to the ability to sustain and simulate detailed abstract models in your mind... but that is a blog post on its own.