Feature collection layer (query)

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Create a feature collection layer to show a query result from a service feature table.

Image of feature collection layer

Use case

Consider a national wireless telecommunications company who wants to improve connectivity within areas of poor coverage. Their cell towers, cell tower radii and state boundaries data are held within service feature tables, which can be queried for states that don't meet a certain threshold of coverage. The query result can be used to create and display a single feature collection layer for analysis of areas requiring improved coverage.

How to use the sample

When launched, this sample displays a map with point features as a feature collection layer. Pan and zoom to explore the map.

How it works

  1. Perform a query using the queryFeaturesAsync() method on a ServiceFeatureTable.
  2. Instantiate a FeatureCollectionTable with the result of the query.
  3. Create a FeatureCollection and add the feature collection table to it.
  4. Create a FeatureCollectionLayer from the feature collection.
  5. Add the feature collection layer to the map's operationalLayers list.

Relevant API

  • FeatureCollection
  • FeatureCollectionLayer
  • FeatureCollectionTable
  • FeatureLayer
  • FeatureQueryResult
  • FeatureTable
  • QueryParameters
  • ServiceFeatureTable

About the data

This application utilizes data from the wildfire feature service. It loads at full extent with features indicating wildfire response point features across the world.

Tags

layer, query, search, table

Sample Code

MainActivity.java
                                                                                                              
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/* Copyright 2017 Esri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.esri.arcgisruntime.sample.featurecollectionlayerquery;

import java.util.concurrent.ExecutionException;

import android.os.Bundle;
import android.util.Log;

import androidx.appcompat.app.AppCompatActivity;
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.concurrent.ListenableFuture;
import com.esri.arcgisruntime.data.FeatureCollection;
import com.esri.arcgisruntime.data.FeatureCollectionTable;
import com.esri.arcgisruntime.data.FeatureQueryResult;
import com.esri.arcgisruntime.data.FeatureTable;
import com.esri.arcgisruntime.data.QueryParameters;
import com.esri.arcgisruntime.data.ServiceFeatureTable;
import com.esri.arcgisruntime.layers.FeatureCollectionLayer;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.BasemapStyle;
import com.esri.arcgisruntime.mapping.view.MapView;

public class MainActivity extends AppCompatActivity {

  private 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);

    // inflate MapView from layout
    mMapView = findViewById(R.id.mapView);

    //initialize map with basemap
    ArcGISMap map = new ArcGISMap(BasemapStyle.ARCGIS_OCEANS);

    //assign map to the map view
    mMapView.setMap(map);

    //initialize service feature table to be queried
    FeatureTable featureTable = new ServiceFeatureTable(getResources().getString(R.string.wildfire_feature_server));

    //create query parameters
    QueryParameters queryParams = new QueryParameters();

    // 1=1 will give all the features from the table
    queryParams.setWhereClause("1=1");

    //query feature from the table
    final ListenableFuture<FeatureQueryResult> queryResult = featureTable.queryFeaturesAsync(queryParams);
    queryResult.addDoneListener(() -> {
      try {
        //create a feature collection table from the query results
        FeatureCollectionTable featureCollectionTable = new FeatureCollectionTable(queryResult.get());

        //create a feature collection from the above feature collection table
        FeatureCollection featureCollection = new FeatureCollection();
        featureCollection.getTables().add(featureCollectionTable);

        //create a feature collection layer
        FeatureCollectionLayer featureCollectionLayer = new FeatureCollectionLayer(featureCollection);

        //add the layer to the operational layers array
        mMapView.getMap().getOperationalLayers().add(featureCollectionLayer);
      } catch (InterruptedException | ExecutionException e) {
        Log.e(TAG, "Error in FeatureQueryResult: " + e.getMessage());
      }
    });
  }

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

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

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

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