Java 1.5/1.6 Game

Okay, i have a good bit of experience using Java and i need a tip before i start my next game... i have already (for a class) prgrammed a Tank game (more of a simulator for maximization protocils) and i am going to make a real game now...

I have just one problem... how do i handle Collisions:
i.e. if my character or whatever runs into a wall. (it will be a simple top-down 2D Shooter, and i need a tip on how to deal make borders and obstuctions work properly.

For one: I have only ever used stuff like 2D arrays to determine if the space is occupied, that unortunately will be too innefective. so i wanna use a fast and simple method for checking for collsions...

any help....

wow... are you serious? I come here and ask just a simple question about collisions and you attack me on my fucking grammar... are you a fucking english teacher?

i am in a cramped working space on a laptop fagass, that means i will miss a couple of fucking keys.... obiously the topic is beyond your comprehension and your only fucking response is "l2Engrish"

go the fuck back to /b/