I need my running java application to be able to detect a web address that is typed into any browser's address bar. This is because I need it to make a decision depending on which website is typed into the bar. It would be best if I can rather get this url through other means aside the address bar. Is this possible with java?

are we talking about a webapplication, that you are running in that browser, or are we talking about a browser written in Java for which you can alter the source code?
if not, I very much doubt it.

the only way to get that information is by installing a keylogger on the victim's computer. And we're NOT going to help you spy on people.

after former answer, I would recommend googling "Keylogger + Java" and you'll see why it won't fly :)

This sounds like you should be writing a browser addon, in which case Java is not appropriate.

And if you decide to go for keylogger in java, read this

I'd go for C instead if I had to, although spying is not a good thing! :D