Style a feature layer

Learn how to apply renderers and label definitions to a feature layer based on attribute values.

style a feature layer

Applications can display feature layer data with different styles to enhance the visualization. The type of Renderer you choose depends on your application. A SimpleRenderer applies the same symbol to all features, a UniqueValueRenderer applies a different symbol to each unique attribute value, and a ClassBreaksRenderer applies a symbol to a range of numeric values. Renderers are responsible for accessing the data and applying the appropriate symbol to each feature when the layer draws. You can also use a LabelDefinition to show attribute information for features. Visit the Styles and data visualization documentation to learn more about styling layers.

You can also author, style and save web maps, web scenes, and layers as portal items and then add them to the map in your application. Visit the following tutorials to learn more about adding portal items.

In this tutorial, you will apply different renderers to enhance the visualization of three feature layers with data for the Santa Monica Mountains: Trailheads with a single symbol, Trails based on elevation change and bike use, and Parks and Open Spaces based on the type of park.

Prerequisites

The following are required for this tutorial:

An ArcGIS account to access API keys. If you don't have an account, sign up for free.
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 Style a feature layer.
  strings.xml
  Use dark colors for code blocks
  1 2 3 4 5
  Change line
  1 2 3 4 5 <resources> <string name="app_name">Style a feature layer</string> </resources>
3. In the Android tool window, open Gradle Scripts > settings.gradle.
  Change the value of rootProject.name to "Style a feature layer".
  settings.gradle
  Expand
  Use dark colors for code blocks
  21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 21 22 23 24
  Change line
  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 = "Style 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 project, set your API key.

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

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

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
Use dark colors for code blocks
Change line
    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 imports statements with the imports needed for this tutorial.

MainActivity.kt
Use dark colors for code blocks
Change lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange lineChange line
package com.example.app

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

import android.graphics.Color
import com.esri.arcgisruntime.ArcGISRuntimeEnvironment
import com.esri.arcgisruntime.arcgisservices.LabelDefinition
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.labeling.ArcadeLabelExpression
import com.esri.arcgisruntime.mapping.view.MapView
import com.esri.arcgisruntime.symbology.ClassBreaksRenderer
import com.esri.arcgisruntime.symbology.ClassBreaksRenderer.ClassBreak
import com.esri.arcgisruntime.symbology.PictureMarkerSymbol
import com.esri.arcgisruntime.symbology.SimpleFillSymbol
import com.esri.arcgisruntime.symbology.SimpleLineSymbol
import com.esri.arcgisruntime.symbology.SimpleRenderer
import com.esri.arcgisruntime.symbology.TextSymbol
import com.esri.arcgisruntime.symbology.UniqueValueRenderer
import com.esri.arcgisruntime.symbology.UniqueValueRenderer.UniqueValue

import com.example.app.databinding.ActivityMainBinding

Among the imports you are pasting into your app is one from the Android API: import android.graphics.Color. You will need this class when setting colors for the symbols.

Create a function to add a feature layer

You can add a feature layer from 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. Once added to the map, feature layers can be symbolized, styled, and labeled in a variety of ways.

Define variables that store feature service URLs used by the app's layers, and then create a helper function to add a layer to the map's list of operational layers. You will use this code throughout the tutorial as you add and symbolize various layers.

Create four read-only String properties: three for accessing feature layers, and a fourth for accessing a static image for use in a picture marker symbol. You will use these resources in future steps.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
    private val parksAndOpenSpaces =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space/FeatureServer/0"
    private val trails =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails/FeatureServer/0"
    private val trailheads =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
    private val trailheadImage =
        "https://static.arcgis.com/images/Symbols/NPS/npsPictograph_0231b.png"
Expand

Add a new function named addFeatureLayer() that takes a feature service URI as an argument, creates a feature layer from the URI, and adds it to the list of the map's operational layers.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
    private fun addFeatureLayer(featureServiceUri: String): FeatureLayer {
        // Create a service feature table from a Uri.
        val serviceFeatureTable = ServiceFeatureTable(featureServiceUri)
        // Create a feature layer from the service feature table.
        val featureLayer = FeatureLayer(serviceFeatureTable)
        // Add the feature layer to the map's list of operational layers.
        map.operationalLayers.add(featureLayer)
        // return the feature layer
        return featureLayer
    }
Expand

Add a layer with a unique value renderer

Create a method to apply a different symbol for each type of park area to the Parks and Open Spaces feature layer.

Add a new function named addOpenSpaceLayer() just after the newly added addFeatureLayer() function.

UniqueValue assigns a symbol to a value or values. A unique value renderer uses a collection of unique values to assign the appropriate symbol for each feature it renderers.

For this example, the renderer uses a feature's TYPE attribute value to apply the correct symbol.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
    private fun addOpenSpaceLayer() {
        // Create a parks and open spaces feature layer and add it to the map view.
        val featureLayer = addFeatureLayer(parksAndOpenSpaces)

        // Create fill symbols.
        val magentaFillSymbol = SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, Color.MAGENTA, null)
        val greenFillSymbol = SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, Color.GREEN, null)
        val blueFillSymbol = SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, Color.BLUE, null)
        val redFillSymbol = SimpleFillSymbol(SimpleFillSymbol.Style.SOLID, Color.RED, null)

        // Create a unique value for natural areas, regional open spaces, local parks, and regional recreation parks.
        val naturalAreas = UniqueValue(
            "Natural Areas",
            "Natural Areas",
            magentaFillSymbol,
            listOf("Natural Areas")
        )

        val regionalOpenSpace = UniqueValue(
            "Regional Open Space",
            "Regional Open Space",
            greenFillSymbol,
            listOf("Regional Open Space")
        )

        val localPark = UniqueValue(
            "Local Park",
            "Local Park",
            blueFillSymbol,
            listOf("Local Park")
        )

        val regionalRecreationPark = UniqueValue(
            "Regional Recreation Park",
            "Regional Recreation Park",
            redFillSymbol,
            listOf("Regional Recreation Park")
        )

        val uniqueValuesList =
            listOf(naturalAreas, regionalOpenSpace, localPark, regionalRecreationPark)

        // Create and assign a unique value renderer to the feature layer.
        val openSpacesUniqueValueRenderer =
            UniqueValueRenderer(listOf("TYPE"), uniqueValuesList, "Open Spaces", null)
        featureLayer.renderer = openSpacesUniqueValueRenderer

        // Set the layer opacity to semi-transparent.
        featureLayer.opacity = 0.2f
    }
Expand

Update setupMap() to call the new addOpenSpaceLayer() function.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.
    // set up your map here. You will call this method from onCreate()
    private fun setupMap() {
        // create a map with the BasemapStyle streets
        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, 72000.0))

        addOpenSpaceLayer()

    }
Expand

Click Run > Run > app to run the app.

When the app opens, Parks and Open Spaces feature layer is added to the map. The map displays the different types of parks and open spaces with four unique symbols.

Add a layer with a class breaks renderer

Create a method to apply a different symbol for each of the five ranges of elevation gain to the Trails feature layer.

Add a new function named addTrailsLayer() just after the addOpenSpaceLayer() function you created above.

A ClassBreak assigns a symbol to a range of values.

For this example, the renderer uses each feature's ELEV_GAIN attribute value to classify it into a defined range (class break) and apply the corresponding symbol.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
    private fun addTrailsLayer() {
        // Create a trails feature layer and add it to the map view.
        val featureLayer = addFeatureLayer(trails)

        // Create simple line symbols.
        val firstClassSymbol = SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.MAGENTA, 3.0f)
        val secondClassSymbol = SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.MAGENTA, 4.0f)
        val thirdClassSymbol = SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.MAGENTA, 5.0f)
        val fourthClassSymbol = SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.MAGENTA, 6.0f)
        val fifthClassSymbol = SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.MAGENTA, 7.0f)

        // Create 5 class breaks.
        val firstClassBreak =
            ClassBreak("Under 500", "0 - 500", 0.0, 500.0, firstClassSymbol)
        val secondClassBreak =
            ClassBreak("501 to 1000", "501 - 1000", 501.0, 1000.0, secondClassSymbol)
        val thirdClassBreak =
            ClassBreak("1001 to 1500", "1001 - 1500", 1001.0, 1500.0, thirdClassSymbol)
        val fourthClassBreak =
            ClassBreak("1501 to 2000", "1501 - 2000", 1501.0, 2000.0, fourthClassSymbol)
        val fifthClassBreak =
            ClassBreak("2001 to 2300", "2001 - 2300", 2001.0, 2300.0, fifthClassSymbol)

        val elevationBreaks = listOf(
            firstClassBreak,
            secondClassBreak,
            thirdClassBreak,
            fourthClassBreak,
            fifthClassBreak
        )

        // Create and assign a class breaks renderer to the feature layer.
        val elevationClassBreaksRenderer = ClassBreaksRenderer("ELEV_GAIN", elevationBreaks)
        featureLayer.renderer = elevationClassBreaksRenderer

        // Set the layer opacity to semi-transparent.
        featureLayer.opacity = 0.75f
    }
Expand

Update setupMap() to call the new addTrailsLayer() function.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.
    // set up your map here. You will call this method from onCreate()
    private fun setupMap() {
        // create a map with the BasemapStyle streets
        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, 72000.0))

        addOpenSpaceLayer()

        addTrailsLayer()

    }
Expand

Click Run > Run > app to run the app.

When the app opens, the Trails feature layer is added to the map. The map displays trails with different symbols depending on trail elevation.

Add layers with definition expressions

You can use a definition expression to define a subset of features to display. Features that do not meet the expression criteria are not displayed by the layer. In the following steps, you will create two methods that use a definition expression to apply a symbol to a subset of features in the Trails feature layer.

FeatureLayer.DefinitionExpression uses a SQL expression to limit the features available for query and display. Your code will create two layers that each display a different subset of trails based on the value for the USE_BIKE field. Trails that allow bikes will be symbolized with a blue symbol ("USE_BIKE = 'Yes'") and those that don't will be yellow ("USE_BIKE = 'No'"). Another way to symbolize these features would be to create a UniqueValueRenderer that applies a different symbol for these values.

Add a function named addBikeOnlyTrailsLayer() with a definition expression to filter for trails that permit bikes. Add this function just after the newly added addTrailsLayer() function.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
    private fun addBikeOnlyTrailsLayer() {
        // Create a trails feature layer and add it to the map view.
        val featureLayer = addFeatureLayer(trails)

        // Write a definition expression to filter for trails that permit the use of bikes.
        featureLayer.definitionExpression = "USE_BIKE = 'Yes'"

        // Create and assign a simple renderer to the feature layer.
        val bikeTrailSymbol =
            SimpleLineSymbol(SimpleLineSymbol.Style.DOT, Color.BLUE, 2.0f)
        val bikeTrailRenderer = SimpleRenderer(bikeTrailSymbol)
        featureLayer.renderer = bikeTrailRenderer
    }
Expand

Add another function named addNoBikeTrailsLayer() with a definition expression to filter for trails that don't allow bikes. Add this function just after the addBikeOnlyTrailsLayer() function.

MainActivity.kt
Expand
Use dark colors for code blocks
Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.Add line.
    private fun addNoBikeTrailsLayer() {
        // Create a trails feature layer and add it to the map view.
        val featureLayer: FeatureLayer = addFeatureLayer(trails)

        // Write a definition expression to filter for trails that don't permit the use of bikes.
        featureLayer.definitionExpression = "USE_BIKE = 'No'"

        // Create and assign a simple renderer to the feature layer.
        val noBikeTrailSymbol =
            SimpleLineSymbol(SimpleLineSymbol.Style.DOT, Color.YELLOW, 2.0f)
        val noBikeTrailRenderer = SimpleRenderer(noBikeTrailSymbol)
        featureLayer.renderer = noBikeTrailRenderer
    }
Expand

Update setupMap() to call the new addBikeOnlyTrailsLayer() and addNoBikeTrailsLayer() functions.
MainActivity.kt
Expand
Use dark colors for code blocks
96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96