How can you handle dart exceptions that have been declared in a library?

Question

Trying to handle an exception in code below:

  findLocation() async {
    final GoogleMapController controller = await _controller.future;

    try {
      gcd.locationFromAddress(userAddress).then((result) => controller
          .animateCamera(CameraUpdate.newCameraPosition(CameraPosition(
              target: LatLng(result[0].latitude, result[0].longitude),
              zoom: 15))));
    } on gcd.NoResultFoundException {
      print("test");
    }
  }

However, when this block runs unsuccessfully, it produces this error:

NoResultFoundException (Could not find any result for the supplied address or coordinates.)

The error points to this code block:

    switch (platformException.code) {
      case 'NOT_FOUND':
        throw NoResultFoundException();
    }
  }

NoResultFoundException is defined in a class with contents:

/// a [Placemark] from coordinates as [double] latitude and longitude
/// or [Location] from address as [String]
class NoResultFoundException implements Exception {
  /// Constructs the [LocationServiceDisabledException]
  const NoResultFoundException();

  @override
  String toString() =>
      'Could not find any result for the supplied address or coordinates.';
}

How can I handle this error in my findLocation() function? (This is the flutter geocoding library by the way, and the exception is defined in the library files.)

Answer 1

You will only get exceptions if you await your call properly.

If you insist on using a then here, then you will need to use .catchError instead of a traditional try/catch block.

A word of advice, don't mix await and then . It's possible, but it's very easy to make mistakes. Stick with one, probably await , since it's easier to handle.