ArcGIS Runtime SDK for Java

Statistical Query

Demonstrates how to query a feature table to get aggregated statistics for a specified field.

How it works

To query statistics on a feature table field:

  1. Create a ServiceFeatureTable from a URL.
  2. Create a list of StatisticDefinitions specifying which field to query against, the aggregate type, and an optional alias.
  3. Create StatisticsQueryParameters passing in the definitions. You can also use the setters to specify an area for the query (geometry) or a custom where clause.
  4. Call featureTable.queryStatisticsAsync(queryParameters) to make the query.
  5. Get the StatisticsQueryResult from the ListenableFuture. To see the stastics, iterate through statisticsQueryResult.iterator() to get the StatisticRecords.
  6. The map of statistics can be retreived with record.getStatistics() for printing or showing in a list view.

Code

/*
 * Copyright 2018 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.samples.featurelayers.statistical_query;

import java.util.Iterator;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.CheckBox;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.layout.CornerRadii;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Paint;
import javafx.stage.Stage;

import com.esri.arcgisruntime.concurrent.ListenableFuture;
import com.esri.arcgisruntime.data.QueryParameters;
import com.esri.arcgisruntime.data.ServiceFeatureTable;
import com.esri.arcgisruntime.data.StatisticDefinition;
import com.esri.arcgisruntime.data.StatisticRecord;
import com.esri.arcgisruntime.data.StatisticType;
import com.esri.arcgisruntime.data.StatisticsQueryParameters;
import com.esri.arcgisruntime.data.StatisticsQueryResult;
import com.esri.arcgisruntime.layers.FeatureLayer;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.Basemap;
import com.esri.arcgisruntime.mapping.view.MapView;

public class StatisticalQuerySample extends Application {

  private MapView mapView;

  @Override
  public void start(Stage stage) {

    try {
      // create stack pane and application scene
      StackPane stackPane = new StackPane();
      Scene scene = new Scene(stackPane);
      scene.getStylesheets().add(getClass().getResource("/css/style.css").toExternalForm());

      // set title, size, and add scene to stage
      stage.setTitle("Statistical Query Sample");
      stage.setWidth(800);
      stage.setHeight(700);
      stage.setScene(scene);
      stage.show();

      // create and set a map with the streets vector basemap
      final ArcGISMap map = new ArcGISMap(Basemap.createStreetsVector());
      mapView = new MapView();
      mapView.setMap(map);

      // create a service feature table using the URL
      String featureServiceURL = "https://sampleserver6.arcgisonline" +
        ".com/arcgis/rest/services/SampleWorldCities/MapServer/0";
      final ServiceFeatureTable featureTable = new ServiceFeatureTable(featureServiceURL);

      // create a feature layer from the service feature table and add it to the map
      FeatureLayer featureLayer = new FeatureLayer(featureTable);
      map.getOperationalLayers().add(featureLayer);

      // create toggle buttons for the query filters
      CheckBox currentExtentFilterToggle = new CheckBox("Only cities in current extent");
      CheckBox populationFilterToggle = new CheckBox("Only cities greater than 5M");

      // create static definitions for all the statistics we want to query on
      // here we specify all statistic types for the "POP" (population) field
      List<StatisticDefinition> statisticDefinitions = Stream.of(StatisticType.values())
        .map(type -> new StatisticDefinition("POP", type, null))
        .collect(Collectors.toList());

      // create a button to perform the statistical query
      Button queryButton = new Button("Get Statistics");
      queryButton.setOnAction(e -> {
        // create statistics query parameters with the definitions
        StatisticsQueryParameters statisticsQueryParameters = new StatisticsQueryParameters(statisticDefinitions);

        if (currentExtentFilterToggle.isSelected()) {
          // set the query geometry to the current visible area
          statisticsQueryParameters.setGeometry(mapView.getVisibleArea());
          // set the spatial relationship to intersects (the default)
          statisticsQueryParameters.setSpatialRelationship(QueryParameters.SpatialRelationship.INTERSECTS);
        }

        if (populationFilterToggle.isSelected()) {
          // set an attribute filter to only retrieve large cities (rank = 1)
          statisticsQueryParameters.setWhereClause("POP_RANK = 1");
        }

        // execute the query
        ListenableFuture<StatisticsQueryResult> query = featureTable.queryStatisticsAsync(statisticsQueryParameters);
        query.addDoneListener(() -> {
          try {
            StatisticsQueryResult result = query.get();
            StringBuilder statistics = new StringBuilder();
            for (Iterator<StatisticRecord> it = result.iterator(); it.hasNext();) {
              StatisticRecord record = it.next();
              record.getStatistics().forEach((key, value) -> statistics.append("\n").append(key).append(": ").append(value));
            }
            Alert alert = new Alert(Alert.AlertType.INFORMATION, statistics.toString());
            alert.setHeaderText("Statistics");
            alert.show();
          } catch (ExecutionException | InterruptedException ex) {
            Alert alert = new Alert(Alert.AlertType.ERROR, ex.getMessage());
            alert.show();
          }
        });
      });

      // layout the controls
      VBox controlsVBox = new VBox(6);
      controlsVBox.setBackground(new Background(new BackgroundFill(Paint.valueOf("rgba(0,0,0,0.3)"), CornerRadii.EMPTY,
          Insets.EMPTY)));
      controlsVBox.setPadding(new Insets(10.0));
      controlsVBox.setAlignment(Pos.CENTER);
      controlsVBox.setMaxSize(220, Double.MIN_VALUE);
      controlsVBox.getStyleClass().add("panel-region");
      currentExtentFilterToggle.setMaxWidth(Double.MAX_VALUE);
      populationFilterToggle.setMaxWidth(Double.MAX_VALUE);
      queryButton.setMaxWidth(Double.MAX_VALUE);
      controlsVBox.getChildren().addAll(currentExtentFilterToggle, populationFilterToggle, queryButton);

      // add the map view and control panel to stack pane
      stackPane.getChildren().addAll(mapView, controlsVBox);
      StackPane.setAlignment(controlsVBox, Pos.TOP_LEFT);
      StackPane.setMargin(controlsVBox, new Insets(10, 0, 0, 10));

    } catch (Exception e) {
      // on any error, display the stack trace
      e.printStackTrace();
    }
  }

  /**
   * Stops and releases all resources used in application.
   */
  @Override
  public void stop() {

    if (mapView != null) {
      mapView.dispose();
    }
  }

  /**
   * Opens and runs application.
   *
   * @param args arguments passed to this application
   */
  public static void main(String[] args) {

    Application.launch(args);
  }

}


In this topic
  1. How it works
  2. Code