That's like saying if you've never driven in a sports car you won't notice that your Ford Ka is slow..
The reason for this is that banks tend not to change software often and the era in which most of their software was written, there weren't many real cross platform alternatives. And now it's just still used "because", in my admittedly limited banking evironment knowledge.
Don't get me wrong, if you like Java then good for you. I just feel that it's not that friendly for a lot of newcomers (although I like case sensitivity, amongst it's other features). My beef is that it encourages OOP, by making procedural fairly non-trivial. But the OOP isn't that brilliant. if you're new to programming diving into OOP might be considered harder to comprehend than procedural, especially if you end up digging in with SWING..
Sam / anyone who wishes to learn to program;
You need to realise that everyone will advocate based on their own experiences. This ends up with "arguments" over trivial things, such as what the best editor / IDE is, or what the best language is. Take what we all say with a pinch of salt and try everything for yourself. Then pick what you think is the best tool.
What works for one person doesn't work for another, is what I'm trying to say. But no matter what you do, use Vim.