How to create Mapbox hotspots and heatmap from lat-long list in Android?

Question

I have a database table containing lat-long data that I need to show as hotspots or as a heatmap on a Mapbox map.

I've checked out the official examples for hotspots and heatmaps, but they are both loading their data from a URL (in geojson format).

What changes do I need to make to their example code (Java and not deprecated), so the hotspot/heatmap data is loaded from my array of LatLng objects instead?

Answer 1

List<LatLng> latLngListFromDatabase = new ArrayList<>();
    List<Feature> featureList = new ArrayList<>();

    for (LatLng latLngObject : latLngListFromDatabase) {
      featureList.add(Feature.fromGeometry(Point.fromLngLat(latLngObject.getLongitude(), latLngObject.getLatitude())));
    }

    loadedMapStyle.addSource(new GeoJsonSource("source-id", FeatureCollection.fromFeatures(featureList)));

Answer 2

To convert your your LatLng objects to Feature use:

var feature = Feature.fromGeometry(Point.fromLngLat(longitude, latitude))

and add them to a featureList. Then you can create an instance of FeatureCollection with:

public static FeatureCollection fromFeatures(@NonNull List<Feature> features)

Finally, there is a constructor in GeoJsonSource in which you can use a FeatureCollection instead of URI:

public GeoJsonSource(String id, FeatureCollection features, GeoJsonOptions options)