Pro Android with Kotlin

182
CHAPTER 8: APIs
", Longitude = " +
location.getLongitude(), e)
}
if (addresses == null || addresses.size == 0) {
// No address was found.
if (errorMessage.isEmpty()) {
errorMessage = "no_address_found"
Log.e("LOG", errorMessage)
}
deliverResultToReceiver(
receiver,
GeocoderConstants.FAILURE_RESULT,
errorMessage)
} else {
val address = addresses[0]
val addressFragments =
(0..address.maxAddressLineIndex).
map { i -> address.getAddressLine(i) }
val addressStr = addressFragments.joinToString(
separator =
System.getProperty("line.separator"))
Log.i("LOG", "address_found")
deliverResultToReceiver(
receiver,
GeocoderConstants.SUCCESS_RESULT,
addressStr)
}
}
private fun deliverResultToReceiver(
receiver:ResultReceiver,
resultCode: Int,
message: String) {
val bundle = Bundle()
bundle.putString(GeocoderConstants.RESULT_DATA_KEY,
message)
receiver.send(resultCode, bundle)
}
}
Again, for productive code, you should use resource strings instead of literals, as shown in 
this example. The service must be registered inside AndroidManifest.xml.
android:exported="false"/>
For using this service, we first build a ResultReceiver class and check the permissions.
For example, we use the last known location to call the service.
class AddressResultReceiver(handler: Handler?) :
ResultReceiver(handler) {
override

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183
CHAPTER 8: APIs
fun onReceiveResult(resultCode: Int,
resultData: Bundle) {
val addressOutput =
resultData.getString(
GeocoderConstants.RESULT_DATA_KEY)
Log.e("LOG", "address result = " +
addressOutput.toString())
...
}
}
val resultReceiver = AddressResultReceiver(null)
fun startFetchAddress(view:View) {
if (checkPermission(
Manifest.permission.ACCESS_COARSE_LOCATION,
Manifest.permission.ACCESS_FINE_LOCATION))
{
fusedLocationClient?.lastLocation?.
addOnSuccessListener(this, {
location: Location? ->
if (location == null) {
// TODO
} else location.apply {
Log.e("LOG", toString())
val intent = Intent(
this@MainActivity,
FetchAddressService::class.java)
intent.putExtra(
GeocoderConstants.RECEIVER,
resultReceiver)
intent.putExtra(
GeocoderConstants.LOCATION_DATA_EXTRA,
this)
startService(intent)
}
})
}
}
You can see we use an explicit intent; that is why we don’t need an intent filter inside the 
service declaration in AndroidManifest.xml.
Using ADB to Fetch Location Information
For development and debugging purposes, you can use ADB to fetch the location 
information of a device connected to your PC or laptop.
./adb shell dumpsys location
For more information on CLI commands, see Chapter 
18
.

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