使用Google Maps Places API从一系列位置查找离当前位置最近的位置

Question

I have an array containing different locations' addresses . I have also retrieved the current location of user.

Out of all the locations in array, i would like to find the one which is nearest . One way could be to compare Lat-Long of all but is there some other way to go about it?

Note: I am not performing nearby location search to retrieve the adresses. Just assume i already have them stored in an array.

Answer 1

You can use Location to determine the distance between two addresses:

private static float distance(LatLng current, LatLng last){
    if(last==null)
        return 0;
    Location cL = new Location("");
    cL.setLatitude(current.latitude);
    cL.setLongitude(current.longitude);

    Location lL = new Location("");
    lL.setLatitude(last.latitude);
    lL.setLongitude(last.longitude);

    return lL.distanceTo(cL);
}

Answer 2

If you need the real nearest location, use Location.distanceBetween .

If you have a lot of locations and require code to execute faster, I'd suggest using this formula:

double diffLat = Math.abs(lat1 - lat2);
double diffLng = Math.abs(lng1 - lng2);
if (diffLng > 180) {
    diffLng = 360 - diffLng;
}
double distanceSquared = diffLat * diffLat + diffLng * diffLng;

Don't calculate sqrt of this, as this is not needed to find (approximatelly) the closest location. Just compare squared values.

The if is there because you may have location with -179 and +179 longitude and these are close to each other.

Depending on the data, you may also try algorithms with binary search on sorted data, but there are 2 dimensions here, so it's not as straightforward as finding int in sorted int[] .