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

Before starting this tutorial:

You need an ArcGIS Location Platform or ArcGIS Online account.
Confirm that your system meets the system requirements.
An IDE for Android development in Kotlin.

Steps

Open an Android Studio project

To start this tutorial, complete the Display a map tutorial. Or download and unzip the Display a map solution in a new folder.
Modify the old project for use in this new tutorial. Expand More info for instructions.
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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  1 2 3 4 5 <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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  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 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.
If you downloaded the solution, get an access token and set the API key.
1. Go to the Create an API key tutorial to obtain a new API key access token. 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 Android Studio: in the Android tool window, open app > java > com.example.app > MainActivity.
3. In the setApiKeyForApp() method, find the ArcGISRuntimeEnvironment.setApiKey("YOUR_ACCESS_TOKEN") call and paste your access token inside the double quotes, replacing YOUR_ACCESS_TOKEN.
  MainActivity.kt
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  Warning
  The access token is stored directly in the code as a convenience for this tutorial. Storing access tokens in the source code is not best practice.

Add import statements

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

MainActivity.kt
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Change lineChange lineChange lineChange lineChange lineChange lineChange linepackage 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

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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Change lineChange line    // 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.

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.

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.

In the setupMap() method, create a ServiceFeatureTable, using a string URL to reference the dataset. You will add Trailheads (points).

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

MainActivity.kt
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    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.

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.

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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        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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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: