Add a feature layer

Before starting this tutorial, you need the following:

1. An ArcGIS Location Platform or ArcGIS Online account.

2. A development and deployment environment that meets the system requirements.

3. An IDE for Android development in Kotlin.

Option 1: Develop the code

Open an Android Studio project

1. Open the project you created by completing the Display a map tutorial.

2. Continue with the following instructions to use a URL to access and display a feature layer in a map.

3. Modify the old project for use in this new tutorial.

   Expand for detailed instructions

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

   2. In the Android view, 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 view, open Gradle Scripts > settings.gradle.kts.

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

      settings.gradle.kts

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      dependencyResolutionManagement {
          repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
          repositories {
              google()
              mavenCentral()
              maven { url = uri("https://esri.jfrog.io/artifactory/arcgis") }
          }
      }
      
      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.

Add import statements

In MainScreen.kt, replace the import statements with the imports needed for this tutorial.

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@file:OptIn(ExperimentalMaterial3Api::class)

package com.example.app.screens

import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.res.stringResource
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.toolkit.geoviewcompose.MapView
import com.example.app.R

Change the view point scale

In MainScreen.kt, inside the top-level function createMap(): Modify the Viewpoint constructor call so it passes a scale parameter more appropriate to tutorial.

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fun createMap(): ArcGISMap {

    return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
        initialViewpoint = Viewpoint(
            latitude = 34.0270,
            longitude = -118.8050,

            scale = 200000.0

        )

    }

}

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 Map Viewer at the top of the page.

2. In createMap(), before the code that creates the ArcGISMap, do the following.

   1. Create strings that hold the URLs to the hosted layers. The URLs are: Trailheads (points), Trails (lines), and Parks and Open Spaces (polygons).

      MainScreen.kt

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      fun createMap(): ArcGISMap {
      
          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"
      
          return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
              initialViewpoint = Viewpoint(
                  latitude = 34.0270,
                  longitude = -118.8050,
      
                  scale = 200000.0
      
              )
      
          }
      
      }

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

      MainScreen.kt

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      fun createMap(): ArcGISMap {
      
          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)
      
          return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
              initialViewpoint = Viewpoint(
                  latitude = 34.0270,
                  longitude = -118.8050,
      
                  scale = 200000.0
      
              )
      
          }
      
      }

   3. You will use FeatureLayers to display the hosted layers on top of the basemap.

      Create three new FeatureLayers using FeatureLayer.createWithFeatureTable(), to which you pass a service feature table.

      MainScreen.kt

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      fun createMap(): ArcGISMap {
      
          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)
      
          val featureLayerPark = FeatureLayer.createWithFeatureTable(parksServiceFeatureTable)
          val featureLayerTrail = FeatureLayer.createWithFeatureTable(trailsServiceFeatureTable)
          val featureLayerTrailHead = FeatureLayer.createWithFeatureTable(trailHeadsServiceFeatureTable)
      
          return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
              initialViewpoint = Viewpoint(
                  latitude = 34.0270,
                  longitude = -118.8050,
      
                  scale = 200000.0
      
              )
      
          }
      
      }

3. In the apply block for ArcGISMap, create a list of these three FeatureLayers, and add them to the map's operationalLayers using addAll().

   More info

   For more information on apply {}, see Kotlin scope functions.

   MainScreen.kt

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   fun createMap(): ArcGISMap {
   
       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)
   
       val featureLayerPark = FeatureLayer.createWithFeatureTable(parksServiceFeatureTable)
       val featureLayerTrail = FeatureLayer.createWithFeatureTable(trailsServiceFeatureTable)
       val featureLayerTrailHead = FeatureLayer.createWithFeatureTable(trailHeadsServiceFeatureTable)
   
       return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
           initialViewpoint = Viewpoint(
               latitude = 34.0270,
               longitude = -118.8050,
   
               scale = 200000.0
   
           )
   
           operationalLayers.addAll(
               listOf(
                   featureLayerPark,
                   featureLayerTrail,
                   featureLayerTrailHead
               )
           )
   
       }
   
   }

4. 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.

Option 2: Download the solution

1. Click the Download solution link in the right-hand side of this page.

2. Unzip the file to a location on your machine.

3. Run Android Studio.

4. Go to File > Open.... Navigate to the solution folder and click Open.

   On Windows: If you are in the Welcome to Android Studio dialog, click Open and navigate to the solution folder. Then click Open.

Since the downloaded solution does not contain authentication credentials, you must first set up authentication to create credentials, and then add the developer credentials to the solution.

Set up authentication

To access the secure ArcGIS location services used in this tutorial, you must implement API key authentication or user authentication using an ArcGIS Location Platform or an ArcGIS Online account.

Set developer credentials in the solution

To allow your app users to access ArcGIS location services, use the developer credentials that you created in the Set up authentication step to authenticate requests for resources.

Run the app

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.