MainActivity.java

private CompletableFuture[] completableFuturesArray;

protected void onCreate(Bundle savedInstanceState) {
        Log.d(LOGTAG, "in onCreate");

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
  
        try { //Load all markers data
            Log.d(LOGTAG, "getting location sources...");
            String file = Utils.openFile(getApplicationContext(), R.raw.location_source);
            locationSourceList = Utils.toJson(file);
            Log.d(LOGTAG, "getting location sources done");
        } catch (IOException e) {
            e.printStackTrace();
        }
  
        completableFutureHashMap = new HashMap<>();
        completableFuturesArray = new CompletableFuture[locationSourceList.size()];
        for (int i = 0; i < locationSourceList.size(); i++) {
            LocationSource locationSource = locationSourceList.get(i);
            CompletableFuture<ViewRenderable> completableFuture = ViewRenderable.builder()
                    .setView(this, R.layout.marker_layout)
                    .build();
            completableFutureHashMap.put(locationSource.getName(), completableFuture);
            completableFuturesArray[i] = completableFuture;
        }
  
        CompletableFuture
                .allOf(completableFuturesArray)
                .handle(
                        (notUsed, throwable) -> {                          
                            if (throwable != null) {
                                DemoUtils.displayError(this, "Unable to load renderables", throwable);
                                return null;
                            }                            
                            hasFinishedLoading = true;
                            return null;
                        }
                );

        // Set an update listener on the Scene that will hide the loading message once a Plane is
        // detected.
        arSceneView
                .getScene()
                .setOnUpdateListener(
                        frameTime -> {
                            if (!hasFinishedLoading) {
                                return;
                            }
                           
                            if (locationScene == null) {
                                locationScene = new LocationScene(this, this, arSceneView);                              
                                locationScene.setAnchorRefreshInterval(ANCHOR_REFRESH_INTERVAL);
                              
                                for(LocationSource locationSource : locationSourceList){
                                    LocationMarker marker = new LocationMarker(locationSource.getLng(), locationSource.getLat(), locationSource.getName(), new Node());
                                    CompletableFuture<ViewRenderable> completableFuture = completableFutureHashMap.get(locationSource.getName());
                                    try {
                                        ViewRenderable viewRenderable = completableFuture.get();
                                        marker.node.setRenderable(viewRenderable);
                                        marker.node.setOnTapListener((v, event) -> Toast.makeText(this, locationSource.getName()+" - distance "+marker.anchorNode.getDistance() + " meters", Toast.LENGTH_LONG).show());
                                        marker.setOnlyRenderWhenWithin(ONLY_RENDER_WHEN_WITHIN);
                                        TextView nameTextView = viewRenderable.getView().findViewById(R.id.txtv_marker_location_name);
                                        nameTextView.setText(n.getLocationMarker().name);
                                        marker.setRenderEvent(n -> {
                                            TextView distanceTextView = viewRenderable.getView().findViewById(R.id.txtv_marker_location_distance);
                                            distanceTextView.setText(getString(R.string.location_distance, n.getDistance()));
                                        });
                                        locationScene.mLocationMarkers.add(marker);
                                    }catch (InterruptedException | ExecutionException ex) {
                                        DemoUtils.displayError(this, "Unable to load renderables", ex);
                                    }
                                }
                            }

                            Frame frame = arSceneView.getArFrame();
                            if (frame == null) {
                                return;
                            }

                            if (frame.getCamera().getTrackingState() != TrackingState.TRACKING) {
                                return;
                            }

                            if (locationScene != null)
                                locationScene.processFrame(frame);
                        });

        ARLocationPermissionHelper.requestPermission(this);
    }