Feature layer selection

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Select features in a feature layer.

Image of feature layer selection

Use case

Selecting features, whether by query or identify, can be an important step both in editing data and visualizing results. One possible use case would be to query a feature layer containing street furniture. A query might look for type "bench" and return a list of bench features contained in the features with an attribute of type bench. These might be selected for further editing (see FeatureQueryResult) or may just be highlighted visually.

How to use the sample

Tap on a feature in the map. All features within a given tolerance (in pixels) of the tap will be selected.

How it works

  1. Create a ServiceFeatureTable from a feature service URL.
  2. Create a FeatureLayer from the service feature table.
  3. Identify nearby features at the clicked location using identifyLayerAsync(featureLayer, clickLocation, tolerance, returnPopupsOnly, maxResults) on the map view.
  4. Select all identified features in the feature layer with selectFeaturesAsync(query, FeatureLayer.SelectionMode.NEW).

Relevant API

  • Feature
  • FeatureLayer
  • ServiceFeatureTable

About the data

This sample uses the Gross Domestic Product, 1960-2016 feature service. Only the 2016 GDP values are shown.

Tags

features, layers, select, selection, tolerance

Sample Code

MainActivity.java
                                                                                                                              
/* Copyright 2016 ESRI
 *
 * All rights reserved under the copyright laws of the United States
 * and applicable international laws, treaties, and conventions.
 *
 * You may freely redistribute and use this sample code, with or
 * without modification, provided you include the original copyright
 * notice and use restrictions.
 *
 * See the Sample code usage restrictions document for further information.
 *
 */

package com.esri.arcgisruntime.sample.featurelayerselection;

import android.graphics.Color;
import android.graphics.Point;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.concurrent.ListenableFuture;
import com.esri.arcgisruntime.data.Feature;
import com.esri.arcgisruntime.data.ServiceFeatureTable;
import com.esri.arcgisruntime.geometry.Envelope;
import com.esri.arcgisruntime.geometry.SpatialReferences;
import com.esri.arcgisruntime.layers.FeatureLayer;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.BasemapStyle;
import com.esri.arcgisruntime.mapping.GeoElement;
import com.esri.arcgisruntime.mapping.Viewpoint;
import com.esri.arcgisruntime.mapping.view.DefaultMapViewOnTouchListener;
import com.esri.arcgisruntime.mapping.view.IdentifyLayerResult;
import com.esri.arcgisruntime.mapping.view.MapView;

public class MainActivity extends AppCompatActivity {

  private static final String TAG = MainActivity.class.getSimpleName();

  private MapView mMapView;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // authentication with an API key or named user is required to access basemaps and other
    // location services
    ArcGISRuntimeEnvironment.setApiKey(BuildConfig.API_KEY);

    // get reference to map view
    mMapView = findViewById(R.id.mapView);
    mMapView.getSelectionProperties().setColor(Color.RED);

    // create a map with the streets basemap
    final ArcGISMap map = new ArcGISMap(BasemapStyle.ARCGIS_STREETS);

    // set the map to be displayed in the MapView
    mMapView.setMap(map);

    // set an initial viewpoint
    mMapView.setViewpoint(new Viewpoint(new Envelope(-1131596.019761, 3893114.069099, 3926705.982140, 7977912.461790,
        SpatialReferences.getWebMercator())));

    // create service feature table and a feature layer from it
    final ServiceFeatureTable serviceFeatureTable = new ServiceFeatureTable(getString(R.string.gdp_per_capita_url));
    final FeatureLayer featureLayer = new FeatureLayer(serviceFeatureTable);

    // add the layer to the map
    map.getOperationalLayers().add(featureLayer);

    // set an on touch listener to listen for click events
    mMapView.setOnTouchListener(new DefaultMapViewOnTouchListener(this, mMapView) {
      @Override
      public boolean onSingleTapConfirmed(MotionEvent motionEvent) {
        featureLayer.clearSelection();
        Point screenPoint = new Point(Math.round(motionEvent.getX()), Math.round(motionEvent.getY()));
        int tolerance = 10;

        ListenableFuture<IdentifyLayerResult> identifyLayerResultFuture = mMapView
            .identifyLayerAsync(featureLayer, screenPoint, tolerance, false, -1);

        identifyLayerResultFuture.addDoneListener(() -> {
          try {
            IdentifyLayerResult identifyLayerResult = identifyLayerResultFuture.get();
            int counter = 0;
            for (GeoElement element : identifyLayerResult.getElements()) {
              if (element instanceof Feature) {
                Feature feature = (Feature) element;
                featureLayer.selectFeature(feature);
                counter++;
                Log.d(TAG, "Selection #: " + counter + " Table name: " + feature.getFeatureTable().getTableName());
              }
            }
            Toast.makeText(getApplicationContext(), counter + " features selected", Toast.LENGTH_SHORT).show();
          } catch (Exception e) {
            Log.e(TAG, "Select feature failed: " + e.getMessage());
          }
        });

        return true;
      }
    });
  }

  @Override
  protected void onPause() {
    mMapView.pause();
    super.onPause();
  }

  @Override
  protected void onResume() {
    super.onResume();
    mMapView.resume();
  }

  @Override
  protected void onDestroy() {
    mMapView.dispose();
    super.onDestroy();
  }
}