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 visual representation of feature table data. Feature layers contain features with a geometry type (point, line, or polygon), and 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 a URL to create, access, and display a feature layer in your app by first creating a local feature table from an ArcGIS Online service: Trailheads (points).

Prerequisites

Steps

Open an Android Studio project

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

2. Modify the old project for use in this new tutorial. Expand More info for instructions.

   More info

   1. On your file system, delete the .idea folder, if present, at the top level of your project.

   2. In the Android tool window, open app > res > values > strings.xml.

      In the <string name="app_name"> element, change the text content to Add a feature layer.

      strings.xml

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      <resources>
      
          <string name="app_name">Add a feature layer</string>
      
      </resources>

   3. In the Android tool window, open Gradle Scripts > settings.gradle.

      Change the value of rootProject.name to "Add a feature layer".

      settings.gradle

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      rootProject.name = "Add a feature layer"
      
      include ':app'

   4. Click File > Sync Project with Gradle files. Android Studio will recognize your changes and create a new .idea folder.

3. If you downloaded the solution project, set your API key.

   More info

   An API Key enables access to services, web maps, and web scenes hosted in ArcGIS Online.

   1. Go to your developer dashboard to get your API key. For these tutorials, use your default API key. It is scoped to include all of the services demonstrated in the tutorials.

   2. In Android Studio: in the Android tool window, open app > java > com.example.app > MainActivity.

   3. In the setApiKeyForApp() method, find the ArcGISRuntimeEnvironment.setApiKey("YOUR_API_KEY") call and paste your API key inside the quotes, replacing YOUR_API_KEY.

      MainActivity.kt

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          override fun onDestroy() {
              mapView.dispose()
              super.onDestroy()
          }
      
          private fun setApiKeyForApp(){
              // set your API key
              // Note: it is not best practice to store API keys in source code. The API key is referenced
              // here for the convenience of this tutorial.
      
              ArcGISRuntimeEnvironment.setApiKey("YOUR_API_KEY")
      
          }
      

Add import statements

Replace app-specific import statements with the imports needed for this tutorial.

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package com.example.app

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity

import com.esri.arcgisruntime.ArcGISRuntimeEnvironment
import com.esri.arcgisruntime.data.ServiceFeatureTable
import com.esri.arcgisruntime.layers.FeatureLayer
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

import com.example.app.databinding.ActivityMainBinding

Change the view point scale

1. In the setupMap() method, modify the Viewpoint constructor call so it passes a scale parameter more appropriate to this tutorial.

   MainActivity.kt

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       // set up your map here. You will call this method from onCreate()
       private fun setupMap() {
           // create a map with the BasemapStyle topographic
           val map = ArcGISMap(BasemapStyle.ARCGIS_TOPOGRAPHIC)
   
           // set the map to be displayed in the layout's MapView
           mapView.map = map
   
           // set the viewpoint, Viewpoint(latitude, longitude, scale)
           mapView.setViewpoint(Viewpoint(34.0270, -118.8050, 200000.0))
   
       }
   

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Create a service feature table to reference feature service data

To display a new data layer (also known as an operational layer) on top of the current basemap, you will create a ServiceFeatureTable using an URL to reference the dataset 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 setupMap() method, create a ServiceFeatureTable, using a string URL to reference the dataset. You will add Trailheads (points).

   More info

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

   MainActivity.kt

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       // set up your map here. You will call this method from onCreate()
       private fun setupMap() {
           // create a map with the BasemapStyle topographic
           val map = ArcGISMap(BasemapStyle.ARCGIS_TOPOGRAPHIC)
   
           // create the service feature table
           val serviceFeatureTable =
               ServiceFeatureTable("https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0")
   

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Create a feature layer to display the hosted data

You will create a new FeatureLayer to display the hosted layer above the basemap.

1. Create a new FeatureLayer using the service feature table and add it to the map as a data (operational) layer.

   If an app has multiple data layers, they are displayed in the order in which they are added to the app.

   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.

   MainActivity.kt

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           // create the service feature table
           val serviceFeatureTable =
               ServiceFeatureTable("https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0")
   
           // create the feature layer using the service feature table
           val featureLayer = FeatureLayer(serviceFeatureTable)
           map.operationalLayers.add(featureLayer)
   

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2. Click Run > Run > app to run the app.

You should see point features (representing trailheads) 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