Create your CarAppService and Session

Your app must extend the CarAppService class and implement its onCreateSession method, which returns a Session instance that corresponds to the current connection to the host:

Kotlin

class HelloWorldService : CarAppService() {
  ...
  override fun onCreateSession(): Session {
      return HelloWorldSession()
  }
  ...
}

Java

public final class HelloWorldService extends CarAppService {
  ...
  @Override
  @NonNull
  public Session onCreateSession() {
      return new HelloWorldSession();
  }
  ...
}

The Session instance returns which Screen instance to use when the app is started for the first time:

Kotlin

class HelloWorldSession : Session() {
  ...
  override fun onCreateScreen(intent: Intent): Screen {
      return HelloWorldScreen(carContext)
  }
  ...
}

Java

public final class HelloWorldSession extends Session {
  ...
  @Override
  @NonNull
  public Screen onCreateScreen(@NonNull Intent intent) {
      return new HelloWorldScreen(getCarContext());
  }
  ...
}

When your car app must start from a screen that isn't the Home or Landing screen, such as when handling deep links, you can use ScreenManager.push before returning from onCreateScreen to pre-seed a back stack of screens. Pre-seeding allows users to navigate back to previous screens from the first screen displayed by your app.

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Set up your project
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Create your start screen