At the end of your act method:

That would work only if the world was unbounded (created using 'super(int, int, int, boolean)' with the boolean set to 'false'). If not, then you need to be a little more tricky: This will place the actor one off of the edge when transporting (so the actor does not bounce back and forth from edge to edge).

The following explains the 'x' part; but, the 'y' part is exactly like it: The code Super_Hippo supplied wraps at -1 and at 600, going to 599 and 0 respectively: ( (x+w)%w, (y+h)%h ) However, we need to wrap at 0 and 599, going to 598 and 1 respectively. By subtracting 1 inside and adding one back outside, we get this: ( ((x-1)+w)%w+1, ((y-1)+h)%h+1 ) This sets the proper lower end for wrapping, but the range is still off by 2 too many, so now we adjust the range (w >> w-2 and h >> h-2): ( ((x-1)+(w-2))%(w-2)+1, ((y-1)+(h-2))%(h-2)+1 } Simplifying, we get this: ( (x+w-3)%(w-2)+1, (y+h-3)%(h-2)+1 ) which is equivalent to what I gave above.