Handle click events

Make data features respond to click events, and use them to change the appearance of a feature based on user interaction.

Write a click event handler

When a click event occurs on a feature layer, the Maps SDK for Android passes a FeatureClickEvent object to the event handler.

Use the FeatureClickEvent.getFeatures() method to get the list of features affected by the click.

Handle feature layer events

Take the following steps to handle events on the Datasets layer. In this example, you apply a blue fill and border to the polygon representing the selected feature.

When you call FeatureLayer.setFeatureStyle(), the style factory function sets the feature style on all features in the dataset. To update the style of a dataset in the event handler, you must call FeatureLayer.setFeatureStyle() to set the updated style on all dataset features.

1. If you haven't already done so, follow the steps in Get Started to create a new map ID and map style. Be sure to enable the Datasets feature layer.

2. Make sure your class implements FeatureLayer.OnFeatureClickListener.

3. Register an event handler for feature click events by calling FeatureLayer.addOnFeatureClickListener().

   Kotlin

   private var datasetLayer: FeatureLayer? = null
   // The globalid of the clicked dataset feature.
   var lastGlobalId: String? = null
   
   override fun onMapReady(googleMap: GoogleMap) {
     // Get the DATASET feature layer.
     datasetLayer = googleMap.getFeatureLayer(FeatureLayerOptions.Builder()
       .featureType(FeatureType.DATASET)
       // Specify the dataset ID.
       .datasetId(YOUR_DATASET_ID)
       .build())
   
     // Register the click event handler for the Datasets layer.
     datasetLayer?.addOnFeatureClickListener(this)
   
     // Apply default style to all features on load to enable clicking.
     styleDatasetsLayer()
   }
   
   // Define the click event handler to set lastGlobalId to globalid of selected feature.
   override fun onFeatureClick(event: FeatureClickEvent) {
     // Get the dataset feature affected by the click.
     val clickFeatures: MutableList<Feature> = event.features
     lastGlobalId = null
     if (clickFeatures.get(0) is DatasetFeature) {
         lastGlobalId = ((clickFeatures.get(0) as DatasetFeature).getDatasetAttributes().get("globalid"))
         // Remember to reset the Style Factory.
         styleDatasetsLayer()
     }
   }

   Java

   private FeatureLayer datasetLayer;
   // The globalid of the clicked dataset feature.
   String lastgobalid = null;
   
   @Override
   public void onMapReady(GoogleMap map) {
   
     // Get the DATASET feature layer.
     datasetLayer = map.getFeatureLayer(new FeatureLayerOptions.Builder()
       .featureType(FeatureType.DATASET)
       // Specify the dataset ID.
       .datasetId(YOUR_DATASET_ID)
       .build());
   
     // Register the click event handler for the Datasets layer.
     datasetLayer.addOnFeatureClickListener(this);
   
     // Apply default style to all features on load to enable clicking.
     styleDatasetsLayer();
   }
   
   @Override
   // Define the click event handler.
   public void onFeatureClick(FeatureClickEvent event) {
     // Get the dataset feature affected by the click.
     List<Feature> clickFeatures = event.getFeatures();
     lastgobalid = null;
     if (clickFeatures.get(0) instanceof DatasetFeature) {
         lastgobalid = ((DatasetFeature) clickFeatures.get(0)).getDatasetAttributes().get("globalid");
         // Remember to reset the Style Factory.
         styleDatasetsLayer();
     }
   }

4. Apply a fill color of blue to the selected feature and green to all other features. Only visible features are clickable.

   Kotlin

   // Set fill and border for all features.
   private fun styleDatasetsLayer() {
       // Create the style factory function.
       val styleFactory = FeatureLayer.StyleFactory { feature: Feature ->
   
       // Check if the feature is an instance of DatasetFeature.
       if (feature is DatasetFeature) {
         val globalIDs: MutableMap<String, String> = feature.getDatasetAttributes()
         // Determine globalid attribute.
         val globalID = globalIDs!!["globalid"]
         // Set default colors to to green.
         var fillColor = 0x800000ff
         var strokeColor = 0xff0000ff
         if (globalID == lastGlobalId) {
           // Color selected area blue.
           fillColor = 0x8000ff00
           strokeColor = 0xff00ff00
         }
         return@StyleFactory FeatureStyle.Builder()
             .fillColor(fillColor)
             .strokeColor(strokeColor)
             .build()
       }
       return@StyleFactory null
     }
   
     // Apply the style factory function to the dataset feature layer.
     datasetLayer?.setFeatureStyle(styleFactory)
   }

   Java

   // Set default green fill and border for all features.
   private void styleDatasetsLayer() {
     // Create the style factory function.
     FeatureLayer.StyleFactory styleFactory = (Feature feature) -> {
   
     // Check if the feature is an instance of DatasetFeature.
     if (feature instanceof DatasetFeature) {
   
       // Check if "globalid" attribute of feature is the "globalid" of clicked feature.
       Map<String, String> globalIDs = ((DatasetFeature) feature).getDatasetAttributes();
       String globalID = globalIDs.get("globalid");
       // Set default colors to green.
       int fillColor = 0x4000ff00;
       int strokeColor = 0xff00ff00;
       if (Objects.equals(globalID, lastgobalid)) {
         // Color selected area blue.
         fillColor = 0x400000ff;
         strokeColor = 0xff0000ff;
       }
       return new FeatureStyle.Builder()
         .fillColor(fillColor)
         .strokeColor(strokeColor)
         .strokeWidth(2)
         .build();
       }
       return null;
     };
   
     // Apply the style factory function to the feature layer.
     datasetLayer.setFeatureStyle(styleFactory);
   }