How to detect if phone is connected to Android Auto

Question

I am making an app that should change its behavior when the phone is connected to an Android Auto. It does not have any Auto capabilities and will not be marketed/submitted as an Android Auto app.

Is there a way to detect if the phone is connected to an Android Auto? I know it is possible for Auto media apps to detect their connection status via a BroadcastReceiver registered for com.google.android.gms.car.media.STATUS action. The documentation is not 100% clear, so will this reliably work also for all other non-Auto apps?

Answer 1

Configuration.UI_MODE_TYPE_CAR is not working on Anroid 12. You can use CarConnection API in the androidx.car.app:app library. But that is too heavy to import entire library only for car connections if you don't need other features.

So I write a piece of code base on the CarConnection to detect Android Auto connection, as below:

class AutoConnectionDetector(val context: Context) {

    companion object {
        const val TAG = "AutoConnectionDetector"

        // columnName for provider to query on connection status
        const val CAR_CONNECTION_STATE = "CarConnectionState"

        // auto app on your phone will send broadcast with this action when connection state changes
        const val ACTION_CAR_CONNECTION_UPDATED = "androidx.car.app.connection.action.CAR_CONNECTION_UPDATED"

        // phone is not connected to car
        const val CONNECTION_TYPE_NOT_CONNECTED = 0

        // phone is connected to Automotive OS
        const val CONNECTION_TYPE_NATIVE = 1

        // phone is connected to Android Auto
        const val CONNECTION_TYPE_PROJECTION = 2

        private const val QUERY_TOKEN = 42

        private const val CAR_CONNECTION_AUTHORITY = "androidx.car.app.connection"

        private val PROJECTION_HOST_URI = Uri.Builder().scheme("content").authority(CAR_CONNECTION_AUTHORITY).build()
    }

    private val carConnectionReceiver = CarConnectionBroadcastReceiver()
    private val carConnectionQueryHandler = CarConnectionQueryHandler(context.contentResolver)

    fun registerCarConnectionReceiver() {
        context.registerReceiver(carConnectionReceiver, IntentFilter(ACTION_CAR_CONNECTION_UPDATED))
        queryForState()
    }

    fun unRegisterCarConnectionReceiver() {
        context.unregisterReceiver(carConnectionReceiver)
    }

    private fun queryForState() {
        carConnectionQueryHandler.startQuery(
            QUERY_TOKEN,
            null,
            PROJECTION_HOST_URI,
            arrayOf(CAR_CONNECTION_STATE),
            null,
            null,
            null
        )
    }

    inner class CarConnectionBroadcastReceiver : BroadcastReceiver() {
      // query for connection state every time the receiver receives the broadcast
        override fun onReceive(context: Context?, intent: Intent?) {
            queryForState()
        }
    }

    internal class CarConnectionQueryHandler(resolver: ContentResolver?) : AsyncQueryHandler(resolver) {
        // notify new queryed connection status when query complete
        override fun onQueryComplete(token: Int, cookie: Any?, response: Cursor?) {
            if (response == null) {
                Log.w(TAG, "Null response from content provider when checking connection to the car, treating as disconnected")
                notifyCarDisconnected()
                return
            }
            val carConnectionTypeColumn = response.getColumnIndex(CAR_CONNECTION_STATE)
            if (carConnectionTypeColumn < 0) {
                Log.w(TAG, "Connection to car response is missing the connection type, treating as disconnected")
                notifyCarDisconnected()
                return
            }
            if (!response.moveToNext()) {
                Log.w(TAG, "Connection to car response is empty, treating as disconnected")
                notifyCarDisconnected()
                return
            }
            val connectionState = response.getInt(carConnectionTypeColumn)
            if (connectionState == CONNECTION_TYPE_NOT_CONNECTED) {
                Log.i(TAG, "Android Auto disconnected")
                notifyCarDisconnected()
            } else {
                Log.i(TAG, "Android Auto connected")
                notifyCarConnected()
            }
        }
    }
}

This solution works on android 6~12. If you need to detect car connection status on android 5, use the Configuration.UI_MODE_TYPE_CAR solution.