Add a feature layer

Learn how to use a URL to access and display a feature layer in a map.

A feature layer is a dataset in a feature service hosted in ArcGIS. Each feature layer contains features with a single geometry type (point, line, or polygon), and a set of attributes. You can use feature layers to store, access, and manage large amounts of geographic data for your applications. You can access features from a feature layer using its underlying feature table.

In this tutorial, you use URLs to access and display three different feature layers hosted in ArcGIS Online:

• Trailheads (points)
• Trails (lines)
• Parks and Open Spaces (polygons)

Prerequisites

Steps

Open a Java project with Gradle

1. To start this tutorial, complete the Display a map tutorial, or download and unzip the Display a map solution into a new folder.

2. Open the build.gradle file as a project in IntelliJ IDEA.

3. If you downloaded the solution, get an access token and set the API key.

   Instructions to set the API Key

   An API Key gives your app access to secure resources used in this tutorial.

   1. Go to the Create an API key tutorial to obtain a new API key access token using your ArcGIS Location Platform or ArcGIS Online account. Ensure that the following privilege is enabled: Location services > Basemaps > Basemap styles service. Copy the access token as it will be used in the next step.

   2. In the IntelliJ IDEA > Project tool window, open src/main/java/com.example.app and double-click App.

   3. In the start() method, set the API key property on the ArcGISRuntimeEnvironment with your access token. Replace YOUR_ACCESS_TOKEN with your copied access token. Be sure to surround your access token with double quotes as it is a string.

      App.java

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          ArcGISRuntimeEnvironment.setApiKey("YOUR_ACCESS_TOKEN");
      

Add import statements

Add import statements to reference the ArcGIS Runtime API classes.

1. In the IntelliJ IDEA > Project tool window, open src/main/java/com.example.app and click App.

2. Add the following imports above the existing imports.

   App.java

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   Add line.Add line.

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   import com.esri.arcgisruntime.data.ServiceFeatureTable;
   import com.esri.arcgisruntime.layers.FeatureLayer;
   
   import com.esri.arcgisruntime.ArcGISRuntimeEnvironment;
   import com.esri.arcgisruntime.mapping.ArcGISMap;
   import com.esri.arcgisruntime.mapping.BasemapStyle;
   import com.esri.arcgisruntime.mapping.Viewpoint;
   import com.esri.arcgisruntime.mapping.view.MapView;
   

Create service feature tables to reference feature service data

To display three new data layers (also known as operational layers) on top of the current basemap, you will create ServiceFeatureTables using URLs to reference datasets hosted in ArcGIS Online.

1. Open a browser and navigate to the URL for Parks and Open Spaces to view metadata about the layer. To display the layer in your ArcGIS Runtime app, you only need the URL.

   More info

   The service page provides information such as the geometry type, the geographic extent, the minimum and maximum scale at which features are visible, and the attributes (fields) it contains. You can preview the layer by clicking on ArcGIS.com Map in the "View In:" list at the top of the page.

2. In the start() method, create three ServiceFeatureTables, using a string URL in each to reference the datasets. You will add: Trailheads (points), Trails (lines), and Parks and Open Spaces (polygons).

   More info

   A ServiceFeatureTable is effectively an in-memory database of the features from the service.

   App.java

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       // set the map on the map view
       mapView.setMap(map);
       mapView.setViewpoint(new Viewpoint(34.02700, -118.80543, 144447.638572));
   
       String parksUrl = "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space_Styled/FeatureServer/0";
       String trailsUrl = "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails_Styled/FeatureServer/0";
       String trailHeadsUrl = "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads_Styled/FeatureServer/0";
   
       ServiceFeatureTable parksServiceFeatureTable = new ServiceFeatureTable(parksUrl);
       ServiceFeatureTable trailsServiceFeatureTable = new ServiceFeatureTable(trailsUrl);
       ServiceFeatureTable trailHeadsServiceFeatureTable = new ServiceFeatureTable(trailHeadsUrl);
   

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Create feature layers to display the hosted data

You will create three new FeatureLayers to display the hosted layers above the basemap.

1. Create three new FeatureLayers using the service feature tables and add them to the map as data (operational) layers.

   Data layers are displayed in the order in which they are added. Polygon layers should be added before layers with lines or points if there's a chance the polygon symbols will obscure features beneath.

   More info

   A FeatureLayer is simply a reference to a feature service and a fast and easy way to add data to a map. It is accessed via a URL which specifies the endpoint. By default, the API will try to load all of the features that fit into the current view.

   App.java

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       ServiceFeatureTable parksServiceFeatureTable = new ServiceFeatureTable(parksUrl);
       ServiceFeatureTable trailsServiceFeatureTable = new ServiceFeatureTable(trailsUrl);
       ServiceFeatureTable trailHeadsServiceFeatureTable = new ServiceFeatureTable(trailHeadsUrl);
   
       map.getOperationalLayers().add(new FeatureLayer(parksServiceFeatureTable));
       map.getOperationalLayers().add(new FeatureLayer(trailsServiceFeatureTable));
       map.getOperationalLayers().add(new FeatureLayer(trailHeadsServiceFeatureTable));
   

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2. Run the app. Ensure to run the app as a Gradle task and not as an application in your IDE. In the Gradle tool window, under Tasks > application, click run.

You should see point, line, and polygon features (representing trailheads, trails, and parks) draw on the map for an area in the Santa Monica Mountains in southern California.

What's next?

Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials:

• Add a point, line, and polygon
• Display a web map
• Display a scene
• Search for an address