รบกวนสอบถาม เรื่องการดึงข้อมูลจาก mysql to map ของ Android หน่อยครับ ว่า ตรงไหนผิดไปหรือป่าว

public class GPSMap4Activity extends FragmentActivity implements OnMapReadyCallback{

    GoogleMap mGoogleMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gpsmap4);

        MapFragment mapFragment = (MapFragment)getFragmentManager().findFragmentById(R.id.map2);
        mapFragment.getMapAsync(this);

    }


    @Override
    public void onMapReady(GoogleMap googleMap) {

        try {
            
            JSONArray data = new JSONArray(getJSON());

            String[] fullName = new String[data.length()];
            Double[] latitude = new Double[data.length()];
            Double[] longtitude = new Double[data.length()];
            for (int i = 0; i<data.length();i++) {
                JSONObject c = data.getJSONObject(i);

                fullName[i] = c.getString("fname");
                latitude[i] = c.getDouble("lat");
                longtitude[i] = c.getDouble("lng");
                googleMap.addMarker(new MarkerOptions()
                        .title(fullName[i])
                        .position(new LatLng(latitude[i], longtitude[i])));
            }

            LatLng thailand = new LatLng(13.75000,100.466667);

            googleMap.setMyLocationEnabled(true);
            googleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(thailand, 13));

            googleMap.addMarker(new MarkerOptions()
                    .title("Thailand")
                    .snippet("The most populous city in Thatland.")
                    .position(thailand));

        } catch (JSONException e){
            e.printStackTrace();
        }


    }

    public String getJSON() {
        String strUrl = "http://27.254.143.125:85/~gpslocation/db_selecttrackinggps2.php";
        URL url =null;
        StringBuffer sb= new StringBuffer();
        try {
            url = new URL(strUrl);
            HttpURLConnection connection = (HttpURLConnection)url.openConnection();
            connection.connect();
            InputStream iStream = connection.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(iStream));
            String line = "";
            while((line = reader.readLine()) != null){
                sb.append(line);
            }
            reader.close();
            iStream.close();
        }catch (MalformedURLException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
        return sb.toString();
    }

    }