Developing an Android Auto App: Parking & Navigation

Created by Mindinventory

What is Android Auto??

Google’s Android Auto platform isn’t its own operating system. It is an Android mobile application developed by Google. It is an extension of a connected Android smartphone to a compatible car that can display some apps, entertainment, and mirror messages on a car’s dashboard.

Android Auto is designed to help keep driver’s attention on the road rather than their smartphone. Functions that are supported by Android auto are navigation, music, telephony, send view SMS messages, voice recognition.

Android Auto is only available on devices with Android 6.0 or later. Android Auto connects to your vehicle over a wired USB connection, but it can also be done wirelessly. You’ll first need an Android smartphone using Android 11 or higher (or a Pixel/Samsung device on Android 9 and up), as well as a vehicle that supports wireless Android Auto.

When you’ll connect your phone to the car’s dashboard head unit, all your auto compatible apps are accessible on the head unit.

Android Auto support the following types of apps:
- Media apps
- Messaging apps
- Navigation, parking, and charging apps

Let’s try to build a parking app:

Declaring dependencies

Add the below dependency in your app-level build.gradle file.

implementation “androidx.car.app:app:1.0.0”

Configure your app’s manifest files

• Declare your CarAppService

The host connects to your app through your CarAppService implementation. You declare this service in your manifest to allow the host to discover and connect to your app.

You also need to declare your app’s category in the category element of your app’s intent filter.

Your app needs to declare either the androidx.car.app.category.PARKING or androidx.car.app.category.CHARGING in category element in the intent filter of its CarAppService.

• Specify the app name and icon

You need to specify an app name and icon that the host can use to represent your app in the system UI.

You can specify the app name and icon that is used to represent your app using label and icon elements of your CarAppService.

• Create your CarAppService and Session

Create the service which needs to extend the CarAppService class.

Implement the CarAppService.onCreateSession method, which returns the Session instance.

• Access the map template

Apps can access the PlaceListMapTemplate, a template that displays a map along with a list of places.

The map can display markers corresponding to the places in the list.

To get access to this template, your app needs to declare the androidx.car.app.MAP_TEMPLATES permission in its AndroidManifest.xml

• Create your start screen

Create the screen by defining classes that extend the Screen class and implementing the Screen.onGetTemplate method, which returns the Template instance representing the state of the UI to display in the car screen.

• Implement screen navigation

The ScreenManager class provides a screen stack that you can use to push screens that can be popped automatically when the user selects a back button in the car screen, or uses the hardware back button available in some cars.

The Action.BACK object is a standard Action that automatically invokes ScreenManager.pop.

• Handle user input

Your app can respond to user input by passing the appropriate listeners to the models.

The onClickNavigate method can then start the default navigation car app by using the CarContext.startCarApp method.

Test your app for Android Auto

Testing your auto supported apps would be difficult so Google provides DHU(Desktop head Unit). The Desktop Head Unit (DHU) enables your development machine to emulate an Android Auto head unit, so that you can run and test Android Auto apps. The DHU runs on Windows, macOS, and Linux systems.

To get started with DHU:

1. Install the Android Auto app on your android phone.
2. Install DHU

• In order to install DHU, open SDK Manager and under Extras, install Android Auto Desktop Head Unit emulator.You can find it in <sdk>/extras/google/auto directory.

3. Running DHU

• Open Auto companion app in your phone and click on the menu icon. You will find only one option available i.e Help & feedback, to enable developer mode tap the header image 10 times. This happens for the first time you install the app.
• When developer mode is ‘on’ you see there are three more options available in the menu. Tap on “Start head unit server” to start the head unit server.
• To make a connection between DHU and head unit server running on our phone set ADB port, type adb forward tcp:5277 tcp:5277in the terminal. Don’t forget this step, otherwise it may show ADB server problem or connection failed error!
• Start the DHU.
  cd <sdk>/extras/google/auto/
  On Linux or OSX: ./desktop-head-unit
  On Windows, desktop-head-unit.exe

You are ready to build your android auto apps and to test them.