Query features on a map using an Arcade expression.
Use case
Arcade is a portable, lightweight, and secure expression language used to create custom content in ArcGIS applications. Like other expression languages, it can perform mathematical calculations, manipulate text, and evaluate logical statements. It also supports multi-statement expressions, variables, and flow control statements. What makes Arcade particularly unique when compared to other expression and scripting languages is its inclusion of feature and geometry data types. This sample uses an Arcade expression to query the number of crimes in a neighborhood in the last 60 days.
How to use the sample
Click on any neighborhood to see the number of crimes in the last 60 days in a callout.
How it works
Create a Portal using the URL.
Create a PortalItem using the Portal and ID.
Create an ArcGISMap using the PortalItem.
Set up a listener for clicks on the map.
Identify the visible layer where it is clicked using mapView.identifyLayerAsync() and get the feature.
Create the following ArcadeExpression: new ArcadeExpression("var crimes = FeatureSetByName(\$map, 'Crime in the last 60 days');\n" + "return Count(Intersects(\$feature, crimes));");
Create an ArcadeEvaluator using the Arcade expression and ArcadeProfile.FORM_CALCULATION.
Create a map of profile variables with $feature and $map as keys.
Call arcadeEvaluator.evaluateAsync() and pass it the profile variables map as parameters.
Once the evaluateAsync() has finished evaluating, get the ArcadeEvaluationResult with listenableFuture.get()
Get the result from the arcade evaluation result with arcadeEvaluationResult.getResult().
Convert the result to a numerical value (integer) and populate the callout with the crime count.
Relevant API
ArcadeEvaluationResult
ArcadeEvaluator
ArcadeExpression
ArcadeProfile
Portal
PortalItem
About the data
This sample uses the Crimes in Police Beats Sample ArcGIS Online Web Map which contains 2 layers for city beats borders, and crimes in the last 60 days as recorded by the Rochester, NY police department.
Additional information
Visit Getting Started on the ArcGIS Developer website to learn more about Arcade expressions.
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/*
* Copyright 2022 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.query_features_with_arcade_expression;
import java.util.HashMap;
import javafx.application.Application;
import javafx.geometry.Point2D;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.ProgressIndicator;
import javafx.scene.input.MouseButton;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
import com.esri.arcgisruntime.arcade.ArcadeEvaluationResult;
import com.esri.arcgisruntime.arcade.ArcadeEvaluator;
import com.esri.arcgisruntime.arcade.ArcadeExpression;
import com.esri.arcgisruntime.arcade.ArcadeProfile;
import com.esri.arcgisruntime.concurrent.ListenableFuture;
import com.esri.arcgisruntime.data.ArcGISFeature;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.layers.Layer;
import com.esri.arcgisruntime.loadable.LoadStatus;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.view.Callout;
import com.esri.arcgisruntime.mapping.view.MapView;
import com.esri.arcgisruntime.portal.Portal;
import com.esri.arcgisruntime.portal.PortalItem;
publicclassQueryFeaturesWithArcadeExpressionSampleextendsApplication{
private MapView mapView;
private ArcGISMap map;
privatefinal String calloutText = "Crimes in the last 60 days: ";
@Overridepublicvoidstart(Stage stage){
try {
// create stack pane and application scenevar stackPane = new StackPane();
var scene = new Scene(stackPane);
// set title, size, and add scene to stage stage.setTitle("Query Features With Arcade Expression Sample");
stage.setWidth(800);
stage.setHeight(700);
stage.setScene(scene);
stage.show();
// authentication with an API key or named user is required to access basemaps and other location services String yourAPIKey = System.getProperty("apiKey");
ArcGISRuntimeEnvironment.setApiKey(yourAPIKey);
// create a progress indicatorvar progressIndicator = new ProgressIndicator();
// create a portal item and use it to create a mapvar portal = new Portal("https://www.arcgis.com/");
var portalItem = new PortalItem(portal, "539d93de54c7422f88f69bfac2aebf7d");
map = new ArcGISMap(portalItem);
// create a map view and set the map to it mapView = new MapView();
mapView.setMap(map);
// set callout leader to appear at the bottom of the callout Callout callout = mapView.getCallout();
callout.setLeaderPosition(Callout.LeaderPosition.BOTTOM);
// wait for the map to finish loading data from portal before accessing its layers map.addDoneLoadingListener(() -> {
if (map.getLoadStatus() == LoadStatus.LOADED) {
Layer policeBeatsLayer = map.getOperationalLayers().get(0);
progressIndicator.setVisible(false);
// if map clicked, evaluate an arcade expression at that point mapView.setOnMouseClicked(event -> {
if (event.getButton() == MouseButton.PRIMARY && event.isStillSincePress()) {
// get the location of the click on the screen Point2D screenPoint = new Point2D(event.getX(), event.getY());
// convert the click location from screen coordinates to map coordinates Point mapPoint = mapView.screenToLocation(screenPoint);
// identify any features on the layer at the clicked locationvar identifyLayerResultFuture = mapView.identifyLayerAsync(policeBeatsLayer,
screenPoint, 0, false);
identifyLayerResultFuture.addDoneListener(() -> {
if (identifyLayerResultFuture.isDone()) {
try {
var identifyLayerResult = identifyLayerResultFuture.get();
// only execute query if the police beats layer has data at the selected pointif (identifyLayerResult.getElements().size() != 0) {
ArcGISFeature feature = (ArcGISFeature) identifyLayerResult.getElements().get(0);
// show callout and text without data callout.setTitle(calloutText);
callout.setDetail("...");
callout.showCalloutAt(mapPoint);
callout.setVisible(true);
// setup arcade expression and evaluator String arcadeExpressionString = "var crimes = FeatureSetByName($map, 'Crime in the last 60 days');\n" +
"return Count(Intersects($feature, crimes));";
var arcadeExpression = new ArcadeExpression(arcadeExpressionString);
var arcadeEvaluator = new ArcadeEvaluator(arcadeExpression, ArcadeProfile.FORM_CALCULATION);
// instantiate key/value pairsvar hashMap = new HashMap<String, Object>();
hashMap.put("$feature", feature);
hashMap.put("$map", mapView.getMap());
// evaluate the arcade expression asynchronously ListenableFuture<ArcadeEvaluationResult> resultFuture = arcadeEvaluator.evaluateAsync(hashMap);
// wait for the expression to finish evaluating before attempting to access it resultFuture.addDoneListener(() -> {
if (resultFuture.isDone()) {
try {
// get result from async method and roundvar arcadeEvaluationResult = resultFuture.get();
var crimesCount = Math.round((double) arcadeEvaluationResult.getResult());
// add data from arcade evaluation to callout callout.setDetail(String.valueOf(crimesCount));
} catch (Exception e) {
thrownew RuntimeException(e);
}
}
});
} else {
// if no data is found at the selected point, hide the callout callout.setVisible(false);
}
} catch (Exception e) {
thrownew RuntimeException(e);
}
}
});
}
});
} elseif (map.getLoadStatus() == LoadStatus.FAILED_TO_LOAD) {
new Alert(Alert.AlertType.ERROR, "Map failed to load").show();
}
});
// add the map view and progress indicator to the stack pane stackPane.getChildren().addAll(mapView, progressIndicator);
} catch (Exception e) {
// on any error, display the stack trace. e.printStackTrace();
}
}
/**
* Stops and releases all resources used in application.
*/@Overridepublicvoidstop(){
if (mapView != null) {
mapView.dispose();
}
}
/**
* Opens and runs application.
*
* @param args arguments passed to this application
*/publicstaticvoidmain(String[] args){
Application.launch(args);
}
}