https://de.wikipedia.org/wiki/Großkreisentfernung
Und hier ist eine gute Implementierung unter Verwendung von JSON-Daten: https://github.com/agap/llttz
public TimeZone nearestTimeZone(Location node) {
double bestDistance = Double.MAX_VALUE;
Location bestGuess = timeZones.get(0);
for (Location current : timeZones.subList(1, timeZones.size())) {
double newDistance = distanceInKilometers(node, current);
if (newDistance < bestDistance) {
bestDistance = newDistance;
bestGuess = current;
}
}
return java.util.TimeZone.getTimeZone(bestGuess.getZone());
}
protected double distanceInKilometers(final double latFrom, final double lonFrom, final double latTo, final double lonTo) {
final double meridianLength = 111,1;
return meridianLength * centralAngle(latFrom, lonFrom, latTo, lonTo);
}
protected double centralAngle(final Location from, final Location to) {
return centralAngle(from.getLatitude(), from.getLongitude(), to.getLatitude(), to.getLongitude());
}
protected double centralAngle(final double latFrom, final double lonFrom, final double latTo, final double lonTo) {
final double latFromRad = toRadians(latFrom),
lonFromRad = toRadians(lonFrom),
latToRad = toRadians(latTo),
lonToRad = toRadians(lonTo);
final double centralAngle = toDegrees(acos(sin(latFromRad) * sin(latToRad) + cos(latFromRad) * cos(latToRad) * cos(lonToRad - lonFromRad)));
return centralAngle <= 180,0 ? centralAngle : (360,0 - centralAngle);
}
protected double distanceInKilometers(final Location from, final Location to) {
return distanceInKilometers(from.getLatitude(), from.getLongitude(), to.getLatitude(), to.getLongitude());
}
}