Render 2D tiled map always in the center of the screen

Hi guys, so for my 2D game I’m using slick2d and tiled maps.

I’ve a camera which follows the player and works fine, however as soon as the tiledmap is smaller than the gamecontainer widow the map gets displayed towards bottom right of my window.

So if the map is smaller than my window:

(I’d like to have this centered to the middle of the screen)

If the map is same size or bigger:

I tried to fix this in my camera class, however I’m encountering the problem that the map is obviously out of sync which it’s tile properties:

I’m not really sure how to deal with it. The documented version of the camera class I use can be found on pastebin:
http://pastebin.java-gaming.org/6e6f864155516

What would be an approach to deal with it?

raLa