Overview
The LocationService class provides location functionality including GPS coordinate retrieval and reverse geocoding to convert coordinates into human-readable addresses. It handles permission checks and supports both modern and legacy Android versions.
Location: com.demodogo.ev_sum_2.services.LocationService
Constructor
class LocationService(private val context: Context)
The Android application context required for accessing location services and geocoding
Data Classes
LocationResult
Represents a location with coordinates and optional address.
data class LocationResult(
val coords: DeviceLocation,
val address: String?
)
The GPS coordinates containing latitude and longitude
The human-readable address, or null if geocoding failed
Methods
hasPermission
Checks if the app has location permissions.
fun hasPermission(): Boolean
Boolean - true if location permissions are granted, false otherwise
Usage Example
val locationService = LocationService(context)
if (locationService.hasPermission()) {
// Proceed with location retrieval
} else {
// Request location permissions
}
getLocationWithAddress
Retrieves the device’s current location with a reverse-geocoded address.
@RequiresPermission(anyOf = [
Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.ACCESS_COARSE_LOCATION
])
suspend fun getLocationWithAddress(): LocationResult
LocationResult - Contains coordinates and optional address
Throws: IllegalStateException if location permission is not granted
This method requires either ACCESS_FINE_LOCATION or ACCESS_COARSE_LOCATION permission. Always check permissions before calling this method.
The address is geocoded using Spanish (Chile) locale (“es-CL”). If geocoding fails, the address will be null, but the coordinates will still be available.
Usage Example
val locationService = LocationService(context)
if (locationService.hasPermission()) {
try {
val result = locationService.getLocationWithAddress()
println("Coordinates: ${result.coords.latitude}, ${result.coords.longitude}")
println("Address: ${result.address ?: "Unknown"}")
} catch (e: IllegalStateException) {
println("Permission error: ${e.message}")
} catch (e: Exception) {
println("Location error: ${e.message}")
}
} else {
// Request permissions
}
reverseGeocodeSafe (Private)
Internal method that performs reverse geocoding with error handling.
private suspend fun reverseGeocodeSafe(lat: Double, lon: Double): String?
This is a private method that handles both modern (API 33+) and legacy Android geocoding APIs. It automatically falls back to null if geocoding fails for any reason.
Android Version Compatibility
The service automatically handles different Android API levels:
- API 33+: Uses the modern callback-based
Geocoder.getFromLocation() method
- API < 33: Uses the deprecated synchronous
Geocoder.getFromLocation() method
Permission Requirements
Before using getLocationWithAddress(), you must request and obtain one of these permissions:
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
Requesting Permissions
val locationPermissionRequest = registerForActivityResult(
ActivityResultContracts.RequestMultiplePermissions()
) { permissions ->
when {
permissions[Manifest.permission.ACCESS_FINE_LOCATION] == true -> {
// Precise location access granted
}
permissions[Manifest.permission.ACCESS_COARSE_LOCATION] == true -> {
// Approximate location access granted
}
else -> {
// No location access granted
}
}
}
locationPermissionRequest.launch(
arrayOf(
Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.ACCESS_COARSE_LOCATION
)
)
Complete Usage Example
class LocationViewModel(application: Application) : AndroidViewModel(application) {
private val locationService = LocationService(application)
private val _locationState = MutableStateFlow<LocationState>(LocationState.Idle)
val locationState: StateFlow<LocationState> = _locationState.asStateFlow()
sealed class LocationState {
object Idle : LocationState()
object Loading : LocationState()
data class Success(val result: LocationResult) : LocationState()
data class Error(val message: String) : LocationState()
object PermissionDenied : LocationState()
}
fun checkAndGetLocation() {
if (!locationService.hasPermission()) {
_locationState.value = LocationState.PermissionDenied
return
}
viewModelScope.launch {
_locationState.value = LocationState.Loading
try {
val result = locationService.getLocationWithAddress()
_locationState.value = LocationState.Success(result)
} catch (e: IllegalStateException) {
_locationState.value = LocationState.Error("Permission not granted")
} catch (e: Exception) {
_locationState.value = LocationState.Error(e.message ?: "Unknown error")
}
}
}
}
Error Handling
SecurityException
Thrown when location permissions are not granted:
try {
val result = locationService.getLocationWithAddress()
} catch (e: IllegalStateException) {
// Handle permission error
showPermissionDialog()
}
Geocoding Failures
Geocoding failures are handled gracefully - the address will be null, but coordinates are still available:
val result = locationService.getLocationWithAddress()
if (result.address == null) {
// Show coordinates only
showLocation(result.coords)
} else {
// Show both coordinates and address
showLocationWithAddress(result.coords, result.address)
}
See Also