Show only Locations Close to my Current Position within 10Kms

Question

In my program i am showing multiple markers on map using JSON Web Service, but now i wish to show only locations close to my current position like within 10Kms.

So here i want to know instead of showing all markers, how can i show closest !

I am placing my whole code, which i am using to place marker on Map V2

public class MainActivity extends FragmentActivity implements LocationListener {

    private static final String LOG_TAG = "JsOn ErRoR";

    private static final String SERVICE_URL = " ";

    protected GoogleMap mapB;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setUpMapIfNeeded();

     // Getting Google Play availability status
        int status = GooglePlayServicesUtil.isGooglePlayServicesAvailable(getBaseContext());

        // Showing status
        if(status!=ConnectionResult.SUCCESS){ // Google Play Services are not available

            int requestCode = 10;
            Dialog dialog = GooglePlayServicesUtil.getErrorDialog(status, this, requestCode);
            dialog.show();

        }else { // Google Play Services are available   

            // Getting reference to the SupportMapFragment of activity_main.xml
            SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);

            // Getting GoogleMap object from the fragment
            mapB = fm.getMap();

            // Enabling MyLocation Layer of Google Map
            mapB.setMyLocationEnabled(true); 

             // Getting LocationManager object from System Service LOCATION_SERVICE
            LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

            // Creating a criteria object to retrieve provider
            Criteria criteria = new Criteria();

            // Getting the name of the best provider
            String provider = locationManager.getBestProvider(criteria, true);

            // Getting Current Location
            Location location = locationManager.getLastKnownLocation(provider);

            if(location!=null){
                    onLocationChanged(location);
            }

            locationManager.requestLocationUpdates(provider, 20000, 0, this);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        setUpMapIfNeeded();
    }

    private void setUpMapIfNeeded() {
        if (mapB == null) {
            mapB = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
                    .getMap();
            if (mapB != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {

        new Thread(new Runnable() {
            public void run() {
                try {
                    retrieveAndAddCities();
                } catch (IOException e) {
                    Log.e(LOG_TAG, "Cannot retrive cities", e);
                    return;
                }
            }
        }).start();
    }

    protected void retrieveAndAddCities() throws IOException {
        HttpURLConnection conn = null;
        final StringBuilder json = new StringBuilder();
        try {
            // Connect to the web service
            URL url = new URL(SERVICE_URL);
            conn = (HttpURLConnection) url.openConnection();
            InputStreamReader in = new InputStreamReader(conn.getInputStream());

            // Read the JSON data into the StringBuilder
            int read;
            char[] buff = new char[1024];
            while ((read = in.read(buff)) != -1) {
                json.append(buff, 0, read);
            }
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error connecting to service", e);
            throw new IOException("Error connecting to service", e);
        } finally {
            if (conn != null) {
                conn.disconnect();
            }
        }

        // Must run this on the UI thread since it's a UI operation.
        runOnUiThread(new Runnable() {
            public void run() {
                try {
                    createMarkersFromJson(json.toString());
                } catch (JSONException e) {
                    Log.e(LOG_TAG, "Error processing JSON", e);
                }
            }
        });
    }

    void createMarkersFromJson(String json) throws JSONException {

        JSONArray jsonArray = new JSONArray(json);
        System.out.print(json);
        List<Marker> markers = new ArrayList<Marker>();

        for (int i = 0; i < jsonArray.length(); i++) {

            JSONObject jsonObj = jsonArray.getJSONObject(i);
            System.out.print(jsonObj.getJSONArray("latlng"));
            Marker marker = mapB.addMarker(new MarkerOptions()
                .title(jsonObj.getString("business_name"))
                .position(new LatLng(
                        jsonObj.getJSONArray("latlng").getDouble(0),
                        jsonObj.getJSONArray("latlng").getDouble(1)))
                        .icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN))
            );
            markers.add(marker);
        }
    }

    @Override
    public void onLocationChanged(Location location) {
        // Getting latitude of the current location
        double latitude = location.getLatitude();

        // Getting longitude of the current location
        double longitude = location.getLongitude();     

        // Creating a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);

        // Showing the current location in Google Map
        mapB.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        // Zoom in the Google Map
        mapB.animateCamera(CameraUpdateFactory.zoomTo(15));

    }

    @Override
    public void onProviderDisabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String provider) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
        // TODO Auto-generated method stub

    }
}

My JSON Looks like:-

[
{
"business_name":"Connaught Place",
"latlng":
[
"28.632777800000000000",
"77.219722199999980000"
]
},
{
"business_name":"Moolchand",
"latlng":
[
"28.568927000000000000",
"77.235073000000060000"
]
}
]

Answer 1

I believe there are number of posts that can tell you about how to calculate the distance between two point, you must try to find your solution before posting it here, well I think this will work for you. its not tested but

void createMarkersFromJson(String json) throws JSONException {

    JSONArray jsonArray = new JSONArray(json);
    System.out.print(json);
    List<Marker> markers = new ArrayList<Marker>();

    for (int i = 0; i < jsonArray.length(); i++) {

        JSONObject jsonObj = jsonArray.getJSONObject(i);
        System.out.print(jsonObj.getJSONArray("latlng"));
Location myLocation = new Location("Current location");

myLocation.setLatitude(mapB.getMyLocation().getLatitude());
myLocation.setLongitude(mapB.getMyLocation().getLongitude());

Location markerLocation= new Location("Destination");

double markerLat = jsonObj.getJSONArray("latlng").getDouble(0);
double markerLong = jsonObj.getJSONArray("latlng").getDouble(1);

markerLocation.setLatitude(markerLat);
markerLocation.setLongitude(markerLong);

float distance = myLocation.distanceTo(markerLocation);
final int KM = 1000;
if(distance <= (10*KM)
{
Marker marker = mapB.addMarker(new MarkerOptions()
            .title(jsonObj.getString("business_name"))
            .position(new LatLng(markerLat,markerLong))
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_GREEN))
        );
        markers.add(marker);
 }
}

Answer 2

Get your current location. Loop through the locations, determining the distance to each (use Location.distanceBetween to calculate it). Sort the locations by distance. Then only add the N closest markers to your map.