Java : Format the distances properly, when compared with location

Question

I am working on a Android application for which the server-side is in Java. When I receive co-ordinates from the user, I am retrieving a list of restaurants, I am calculating the distance from the user, and sorting them in ascending fashion.

Right now, everything works. The only problem is that the distance computed has a very high-sensitivity. What I am looking for is, distance shown in this manner i.e 1.2km, 200m, 12.2km, etc , which is calculating and appending Km or Meters appropriately. How can I achieve this?

Output currently is :

Restaurant distance is 6026.203669933703
Restaurant distance is 1.0248447083638768
Restaurant distance is 1.0248447083638768
Restaurant distance is 1.0248447083638768

Code for calculation & sorting :

 @Override
    public List<Restaurant> getNearbyRestaurants(double longitude, double latitude) {

        final int R = 6371; // Radius of the earth
        List<Restaurant> restaurantList = this.listRestaurants();
        List<Restaurant> nearbyRestaurantList = new ArrayList<>();
        for(Restaurant restaurant : restaurantList){
            Double latDistance = toRad(latitude-restaurant.getLatitude());
            Double lonDistance = toRad(longitude-restaurant.getLongitude());
            Double a = Math.sin(latDistance / 2) * Math.sin(latDistance / 2) +
                    Math.cos(toRad(latitude)) * Math.cos(toRad(restaurant.getLatitude())) *
                            Math.sin(lonDistance / 2) * Math.sin(lonDistance / 2);
            Double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
            Double distance = R * c;
            restaurant.setDistanceFromUser(distance);
            if(distance < 10){
                nearbyRestaurantList.add(restaurant);
            }
        }
        if(!(nearbyRestaurantList.isEmpty())) {

            Collections.sort(nearbyRestaurantList, new Comparator<Restaurant>() {
                @Override
                public int compare(Restaurant o1, Restaurant o2) {
                    if (o1.getDistanceFromUser() > o2.getDistanceFromUser()) {
                        return 1;
                    }
                    if (o1.getDistanceFromUser() < o2.getDistanceFromUser()) {
                        return -1;
                    }
                    return 0;
                }
            });


            for(Restaurant restaurant : restaurantList){
                System.out.println("Restaurant distance is "+restaurant.getDistanceFromUser());
            }
            return nearbyRestaurantList;
        }
        return null;
    }

Kindly let me know what am I missing. Thanks a lot. :-)

Answer 1

If the distance is below 1000m then depending on the application use either the exact value of the integral meters, or round to the next 10 meters:

473.343 -> 470m or 473 depending on the goal of your application

If the distance is above 1km but below 100km use one digit after decimal point:

1.5km, 10.3km, 99.5km

If above 100km round to integral kilometers: 101km, 9453km