A quick look at the jscience API doesn't reveal any method of calculating distance, but it may be buried in there somewhere.
I've used the jcoord library before now which has a nice and simple interface, e.g.
LatLng centre = new LatLng(lat, lon);
LatLon somePoi = new LatLon(poiLat, poiLon);
Double dist = centre.distance(somePoi);
Note however, that it looks as though the project website has been hacked, so be careful! I can send along my copy of the jar if it helps.
A more complete set of libraries comes from the GeoTools project, where they use a library by the name of JTS. See http://docs.geotools.org/latest/user...y/api/jts.html
for an example of calculating distance with these libraries.
In the end, it may be just as easy to implement the Haversine formula yourself, depending on how accurate you need things to be, the coordinate reference systems being used, where on the Earth you want it to work, etc.