Erald Guri

I have an app where I have to use websockets to update markers on google map in real time. I successfully did the connection with web sockets and in the response I'm getting the json string. I parsed to JSONObject and when I debug I see that all the data in the json are coming but the problem is when I have to add markers. The error is:
 e: "com.google.maps.api.android.lib6.common.apiexception.c: Not on the main thread"

After connection to websocket I did the following code to get the data:
private OkHttpClient client;    private EchoWebSocketListener webSocketListener;    private static final int NORMAL_CLOSURE_STATUS = 1000;    public void startWebSocketConnection() {        client = new OkHttpClient.Builder()                .readTimeout(3000, TimeUnit.MILLISECONDS)                .build();        webSocketListener = new EchoWebSocketListener(new EchoWebSocketListener.SocketClientListener() {            @Override            public void onConnected(WebSocket webSocket, okhttp3.Response response) {                Log.d("Connected :", response.toString());            }            @Override            public void getMessage(String message) {                Log.d("Received", message);                List<ClusterItem> clusterItems = new ArrayList<>();                try {                    JSONObject jsonObject = (JSONObject) new JSONTokener(message).nextValue();                    //String vehicle_id = jsonObject.getString("id");                    String vehicle_class = jsonObject.getString("vehicle_class");                    String kemlercode = jsonObject.getString("kemlercode");                    String vehicle_speed = jsonObject.getString("vehicle_speed");                    JSONObject newJsonObject = jsonObject.getJSONObject("portalMetadata");                    String portal_id = newJsonObject.getString("id");                    String portalName = newJsonObject.getString("portalName");                    String location = newJsonObject.getString("location");                    String[] coordinates = location.split(",");                    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {                        double[] locations = Stream.of(coordinates).mapToDouble(Double::parseDouble).toArray();                        double latitude = locations[0];                        double longitude = locations[1];                        MarkerOptions markerOptions = new MarkerOptions();                        LatLng latLng = new LatLng(latitude, longitude);                        markerOptions.position(latLng);                        Marker marker = mGoogleMap.addMarker(markerOptions);                        cameraConfigurations(latLng);                        ClusterItem loc = new ClusterItem(latitude, longitude, vehicle_class, kemlercode);                        marker.remove();                        marker.showInfoWindow();                        clusterItems.add(loc);                        mClusterManager.addItem(loc);                        mGoogleMap.setOnMarkerClickListener(mClusterManager);                        mGoogleMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 5.0f));                        markers.add(marker);                        setClusterManager(mClusterManager, clusterItems);                        mGoogleMap.setOnCameraIdleListener(mClusterManager);                    }                } catch (JSONException e) {                    e.printStackTrace();                }            }            @Override            public void onFailure(WebSocket webSocket, String reason) {                Log.d("Failure :", reason);            }            @Override            public void closingOrClosed(boolean isClosed, WebSocket webSocket, String reason, int code) {                Log.d("ClosingOrClosed :", isClosed ? "Closed" : "closing");            }        });        Request request = new Request.Builder().url(SOCKET_URL).build();        client.newWebSocket(request, webSocketListener);    }

and I run the websocket in the runonuithread() on onCreate as in the following:
runOnUiThread(this::startWebSocketConnection);

I'm using okHttp library to perform communications with websockets. What I'm doing wrong here. Does anyone have any suggestion what I need to improve. Any help will be appreciated. Thanks in advance.