LocationReceiver.kt

class LocationReceiver : BroadcastReceiver() {

    override fun onReceive(context: Context?, intent: Intent?) {
        val action: String? = intent?.action
        if (ACTION_PROCESS_UPDATE == action) {
            val result: LocationResult? = LocationResult.extractResult(intent)
            val location: Location? = result?.lastLocation
            val locationString = "${location?.latitude}/${location?.longitude}"
            try {
                MainActivity.instance?.updateTextView(locationString)
            } catch (e: Exception) {
                Toast.makeText(context, "$e, locationString", Toast.LENGTH_SHORT).show()
            }
        }

    }

    companion object {
        const val ACTION_PROCESS_UPDATE = "com.agforce.gps.UPDATE_LOCATION"
    }
}

MainGpsActivity.kt

class MainActivity : AppCompatActivity() {

    lateinit var fusedClient: FusedLocationProviderClient

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // this is awful!
        instance = this

        Dexter.withActivity(this)
            .withPermission(android.Manifest.permission.ACCESS_FINE_LOCATION)
            .withListener(object: PermissionListener{
                override fun onPermissionGranted(response: PermissionGrantedResponse?) {
                    updateLocation()
                }

                override fun onPermissionRationaleShouldBeShown(
                    permission: PermissionRequest?,
                    token: PermissionToken?
                ) {
                    Toast.makeText(this@MainActivity, "Please grand location permission", Toast.LENGTH_SHORT).show()
                }

                override fun onPermissionDenied(response: PermissionDeniedResponse?) {
                    Toast.makeText(this@MainActivity, "Please grand location permission", Toast.LENGTH_SHORT).show()
                }
            }).check()
    }

    private fun updateLocation() {
        fusedClient = LocationServices.getFusedLocationProviderClient(this)
        if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return
        }
        fusedClient.requestLocationUpdates(buildLocationRequest(), getPendingIntent())
    }

    private fun getPendingIntent(): PendingIntent? {
        val intent = Intent(this, LocationReceiver::class.java)
        intent.action = LocationReceiver.ACTION_PROCESS_UPDATE
        return PendingIntent.getBroadcast(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
    }

    private fun buildLocationRequest() = LocationRequest().apply {
            priority = LocationRequest.PRIORITY_HIGH_ACCURACY
            interval = UPDATES_INTERVAL
            fastestInterval = FASTEST_INTERVAL
            smallestDisplacement = SMALLEST_DISPLACEMENT
    }

    fun updateTextView(locationString: String) {

    }

    companion object {

        const val UPDATES_INTERVAL = 5 * 1000L
        const val FASTEST_INTERVAL = 2 * 1000L
        const val SMALLEST_DISPLACEMENT = 10f

        var instance: MainActivity? = null
    }
}