If you study hard, you can learn a lot in a year, but do not expect to be proficient. I learnt German at school, along with the grammar.
When I moved there, I had to speak to Germans all day in German only. Remembering grammar took too long, so I abandoned that and just spoke the words I knew, guessing when to use der, die or das. After a year, with the help of a smallpocket dictionary, an old tv set on which I watched German cartoons, and some delightful German girlfriends, I was able to speak quite well about most things in German. I was relatively fluent, but that was partly because I did not speak English for that year.