Why does ByteData.view(buffer) throw NoSuchMethodError: Class 'String' has no instance method 'asByteData' - casting

Question

I am trying to read UDP data and converting it to a float.
I know I need to
Receive the Datagram from RawDatagramSocket
Get the ByteBuffer from the Datagram
Convert the ByteBuffer to ByteData
use the getFloat32 method on the ByteData
Here is the broken code:
import 'dart:io';
import 'dart:typed_data';
import 'dart:mirrors';
getTypeName(dynamic obj) {
return reflect(obj).type.reflectedType.toString();
}
void main(List<String> args){
RawDatagramSocket.bind("192.168.1.1", 4444).then((RawDatagramSocket socket){
print('Datagram socket ready to receive');
print('${socket.address.address}:${socket.port}');
socket.listen((RawSocketEvent e){
Datagram d = socket.receive();
if (d == null) return;
ByteBuffer buffer = getTypeName(d.data.buffer);
ByteData bdata = new ByteData.view(buffer);
});
});
}
Here is the debugging code:
import 'dart:io';
import 'dart:typed_data';
import 'dart:mirrors';
getTypeName(dynamic obj) {
return reflect(obj).type.reflectedType.toString();
}
void main(List<String> args){
RawDatagramSocket.bind("192.168.1.1", 4444).then((RawDatagramSocket socket){
print('Datagram socket ready to receive');
print('${socket.address.address}:${socket.port}');
socket.listen((RawSocketEvent e){
Datagram d = socket.receive();
if (d == null) return;
print(d.data);
});
});
}
If I initiate netcat using the following command nc -u 192.168.1.1 4444 and send the data '1111', I get the following printed out from the debug code:
[49, 49, 49, 49, 10]
I understand those values are the assai characters of '1111' followed by a carriage return.
The problem is, when I run the 'broken code', I end up getting the following message:
Unhandled exception:
NoSuchMethodError: Class 'String' has no instance method 'asByteData'.
Receiver: "_ByteBuffer"
Tried calling: asByteData(0, null)
#0 Object._noSuchMethod (dart:core-patch/object_patch.dart:43)
#1 Object.noSuchMethod (dart:core-patch/object_patch.dart:47)
#2 new ByteData.view (dart:typed_data:449)
#3 main.<anonymous closure>.<anonymous closure> (file:///Users/iProgram/test.dart:17:25)
#4 _RootZone.runUnaryGuarded (dart:async/zone.dart:1307)
#5 _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:330)
#6 _BufferingStreamSubscription._add (dart:async/stream_impl.dart:257)
#7 _StreamController&&_SyncStreamControllerDispatch._sendData (dart:async/stream_controller.dart:796)
#8 _StreamController._add (dart:async/stream_controller.dart:667)
#9 _StreamController.add (dart:async/stream_controller.dart:613)
#10 new _RawDatagramSocket.<anonymous closure> (dart:io-patch/socket_patch.dart:1699)
#11 _NativeSocket.issueReadEvent.issue (dart:io-patch/socket_patch.dart:760)
#12 _microtaskLoop (dart:async/schedule_microtask.dart:41)
#13 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#14 _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:99)
#15 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:152)
The question is, why am I getting the error Class 'String' has no instance method 'asByteData' when I am not using a string or the asByteData command?
I have been using the following documentation: Dart - ByteData
Thanks

Answer 1

why am I getting the error Class 'String' has no instance method 'asByteData' when I am not using a string or the asByteData command?
The call stack shows what's happening here:
Tried calling: asByteData(0, null)
#0 Object._noSuchMethod (dart:core-patch/object_patch.dart:43)
#1 Object.noSuchMethod (dart:core-patch/object_patch.dart:47)
#2 new ByteData.view (dart:typed_data:449)
You're calling new ByteData.view which is internally calling asByteData.
The ByteData.view constructor takes a ByteBuffer but you're passing it a string:
ByteBuffer buffer = getTypeName(d.data.buffer);
Although you've written ByteBuffer here, your getTypeName() function is actually returning a String:
return reflect(obj).type.reflectedType.toString();