Add a feature layer

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

A map contains layers of geographic data. A map contains a basemap layer and, optionally, one or more data layers. This tutorial shows you how to access and display a feature layer in a map. You access feature layers with an item ID or URL. You will use URLs to access the Trailheads, Trails, and Parks and Open Spaces feature layers and display them 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.

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 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 setApiKey() function, find the ApiKey.create() call and paste your API key inside the quotes, replacing YOUR_API_KEY.

      MainActivity.kt

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          private fun setApiKey() {
              // It is not best practice to store API keys in source code. We have you insert one here
              // to streamline this tutorial.
      
              ArcGISEnvironment.apiKey = ApiKey.create("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 android.util.Log
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.arcgismaps.data.ServiceFeatureTable
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.mapping.view.MapView
import com.example.app.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

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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       private fun setupMap() {
           // create a map with the BasemapStyle topographic
           val map = ArcGISMap(BasemapStyle.ArcGISTopographic)
           mapView.map = map
   
           // set the viewpoint, Viewpoint(latitude, longitude, scale)
           mapView.setViewpoint(Viewpoint(34.0270, -118.8050, 200000.0))
   

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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 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 Android Studio, open app > java > com.example.app > MainActivity.

3. In the setupMap() function, add code that defines the URLs to the hosted layers. You will add: Trailheads (points), Trails (lines), and Parks and Open Spaces (polygons).

   MainActivity.kt

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           // set the viewpoint, Viewpoint(latitude, longitude, scale)
           mapView.setViewpoint(Viewpoint(34.0270, -118.8050, 200000.0))
   
           val parksUrl =
               "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space_Styled/FeatureServer/0"
           val trailsUrl =
               "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails_Styled/FeatureServer/0"
           val trailHeadsUrl =
               "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads_Styled/FeatureServer/0"
   

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4. Create three ServiceFeatureTable objects, using a string URL to reference the datasets.

   More info

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

   MainActivity.kt

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           val parksUrl =
               "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space_Styled/FeatureServer/0"
           val trailsUrl =
               "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails_Styled/FeatureServer/0"
           val trailHeadsUrl =
               "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads_Styled/FeatureServer/0"
   
           val parksServiceFeatureTable = ServiceFeatureTable(parksUrl)
           val trailsServiceFeatureTable = ServiceFeatureTable(trailsUrl)
           val trailHeadsServiceFeatureTable = ServiceFeatureTable(trailHeadsUrl)
   

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Create feature layers to display the hosted data

You will create new FeatureLayers to display the hosted layers 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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           val parksServiceFeatureTable = ServiceFeatureTable(parksUrl)
           val trailsServiceFeatureTable = ServiceFeatureTable(trailsUrl)
           val trailHeadsServiceFeatureTable = ServiceFeatureTable(trailHeadsUrl)
   
           map.operationalLayers.add(FeatureLayer.createWithFeatureTable(parksServiceFeatureTable))
           map.operationalLayers.add(FeatureLayer.createWithFeatureTable(trailsServiceFeatureTable))
           map.operationalLayers.add(FeatureLayer.createWithFeatureTable(trailHeadsServiceFeatureTable))
   

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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