Terrain - loading from an ESRI file

Hi, I'm new to jME and plan to write a small app with a terrain and a few buildings. I have a terrain in a ESRI format (text file). The header of the file looks like this:

ncols        256

nrows        230

xllcorner    292795.05

yllcorner    6694715.69

cellsize      44.2

My question is about the com.jmex.terrain.util.AbstractHeightMap… First of all the terrain has to be squared (e.g. 256x256), why is that? Is it because TerrainPage uses a quadtree? But that's not important… What I really was wondering about is that the local variable heightMap in AbstractHeightMap is a one dimentional int array. The use of indexing is ok, but why is it int? My textfile with height values are in meters. f.eks. 248.19m, 259.79m… Why is this heightMap variable not a float array? Is there a easy way I can get more detail than just meters/int?