Identify Graphics Hit Test

The Identify Graphics Hit Test sample demonstrates how to create a Graphic and add it to a GraphicOverlay where it can be identified from the MapView.

Features

• ArcGISMap
• MapView
• DefaultMapViewOnTouchListener
• Graphic
• GraphicsOverlay

Developer Pattern

Graphics

Graphics represent graphic elements used in graphic overlays on the MapView. Graphics are contained in a modifiable List for graphics on a GraphicsOverlay. The ListenableList interface defines a listenable List of graphics that can be notified when items are being added or removed from the List.

// create list of graphics
ListenableList<Graphic> graphics = grOverlay.getGraphics();
// add graphic to graphics overlay
graphics.add(graphic);
// add graphics overlay to the MapView
mMapView.getGraphicsOverlays().add(grOverlay);

Identify Graphics Overlay

You can identify on a graphics overlay from the MapView.identifyOnGraphicsOverlay() method which returns a ListenableFuture<List<Graphic>>. Futures are an abstraction for asynchronous event driven systems that the Android platform provides. The method returns immediately as a wrapper around the List<Graphic>, once the asynchronous event is completed you can access it with ListenableFuture.get().

// identify graphics on the graphics overlay
final ListenableFuture<IdentifyGraphicsOverlayResult> identifyGraphic = mMapView.identifyGraphicsOverlayAsync(grOverlay, screenPoint, 10.0, false, 2);

identifyGraphic.addDoneListener(new Runnable() {
    @Override
    public void run() {
        try {
            IdentifyGraphicsOverlayResult grOverlayResult = identifyGraphic.get();
            // get the list of graphics returned by identify graphic overlay
            List<Graphic> graphic = grOverlayResult.getGraphics();
            // get size of list in results
            int identifyResultSize = graphic.size();
            if(!graphic.isEmpty()){
                // show a toast message if graphic was returned
                Toast.makeText(getApplicationContext(), "Tapped on " + identifyResultSize + " Graphic", Toast.LENGTH_SHORT).show();
            }
        }catch(InterruptedException | ExecutionException ie){
            ie.printStackTrace();
        }

    }
});