使用@shieldstroy发布的问题中此答案所述算法,该算法使用Great Circle Distance,我已将其示例成功运行。
以下是Comparator
:
public class SortPlaces implements Comparator<Place> {
LatLng currentLoc;
public SortPlaces(LatLng current){
currentLoc = current;
}
@Override
public int compare(final Place place1, final Place place2) {
double lat1 = place1.latlng.latitude;
double lon1 = place1.latlng.longitude;
double lat2 = place2.latlng.latitude;
double lon2 = place2.latlng.longitude;
double distanceToPlace1 = distance(currentLoc.latitude, currentLoc.longitude, lat1, lon1);
double distanceToPlace2 = distance(currentLoc.latitude, currentLoc.longitude, lat2, lon2);
return (int) (distanceToPlace1 - distanceToPlace2);
}
public double distance(double fromLat, double fromLon, double toLat, double toLon) {
double radius = 6378137;
double deltaLat = toLat - fromLat;
double deltaLon = toLon - fromLon;
double angle = 2 * Math.asin( Math.sqrt(
Math.pow(Math.sin(deltaLat/2), 2) +
Math.cos(fromLat) * Math.cos(toLat) *
Math.pow(Math.sin(deltaLon/2), 2) ) );
return radius * angle;
}
}
这里是高层次的代码,我只是把它放在 onCreate()
中:
double lat = 37.77657;
double lng = -122.417506;
LatLng latLng = new LatLng(lat, lng);
ArrayList<Place> places = new ArrayList<Place>();
places.add(new Place("New York", new LatLng(40.571256,73.98369)));
places.add(new Place("Colorado", new LatLng(39.260658,-105.101615)));
places.add(new Place("Los Angeles", new LatLng(33.986816,118.473819)));
for (Place p: places){
Log.i("Places before sorting", "Place: " + p.name);
}
Collections.sort(places, new SortPlaces(latLng));
for (Place p: places){
Log.i("Places after sorting", "Place: " + p.name);
}
这是日志输出:
04-17 23:04:16.074 12963-12963/com.maptest.daniel.maptest I/Places before sorting﹕ Place: New York
04-17 23:04:16.074 12963-12963/com.maptest.daniel.maptest I/Places before sorting﹕ Place: Colorado
04-17 23:04:16.074 12963-12963/com.maptest.daniel.maptest I/Places before sorting﹕ Place: Los Angeles
04-17 23:04:16.074 12963-12963/com.maptest.daniel.maptest I/Places after sorting﹕ Place: Los Angeles
04-17 23:04:16.074 12963-12963/com.maptest.daniel.maptest I/Places after sorting﹕ Place: Colorado
04-17 23:04:16.074 12963-12963/com.maptest.daniel.maptest I/Places after sorting﹕ Place: New York