Java: What is a good data structure for storing a coordinate map for an infinite game world?

Question

I am used to coding in PHP but I am not really proficient with Java and this has been a problem for some time now. I expect it to be a fairly easy solution, however I cannot

Answer 1

you could try a QuadTree (nice example here: http://www.mikechambers.com/blog/2011/03/21/javascript-quadtree-implementation/ )