How to check network connectivity in Flutter? - flutter

Question

I want to check if user has internet connection and want it to be dynamic. Customisable messages will be shown to user according to it.
ElevatedButton(
onPressed: () async {
ans = await InternetConnectionChecker().hasConnection;
print(ans);
},
child: const Text('Fetch Data'),
),
I can check it when clicked on the button by the user but I want it to be automatic when user hops on the home page.
I tried putting
ans = await InternetConnectionChecker().hasConnection;
print(ans);
in initState but it doesn't work. Any suggestions as to how should I improve it?
EDIT :
I tried the first solution and on click of a button I get all the results perfectly
onPressed: () async {
var connectivityResult = await (Connectivity().checkConnectivity());
var subscription = Connectivity()
.onConnectivityChanged
.listen((ConnectivityResult result) {
print("Changed to $result");
});
if (connectivityResult == ConnectivityResult.mobile) {
// I am connected to a mobile network.
print("Mobile");
} else if (connectivityResult == ConnectivityResult.wifi) {
// I am connected to a wifi network.
print("Wifi");
}
},
It shows none when no internet is there. To mobile when connected to mobile hotspot and wifi when connected to wifi network.
But my issue still remains that I want to check internet connection when a user comes to my home page.
I tried this :
var subscription;
#override
initState() async {
super.initState();
print("hlo");
var connectivityResult = await (Connectivity().checkConnectivity());
var subscription = Connectivity()
.onConnectivityChanged
.listen((ConnectivityResult result) {
print("Changed to $result");
});
}
But this doesn't work. What am I dooing wrong? Can i improve this?

Answer 1

This plugin allows Flutter apps to discover network connectivity and configure themselves accordingly. It can distinguish between cellular vs WiFi connection. check here
connectivity_plus 3.0.2
import 'package:connectivity_plus/connectivity_plus.dart';
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.mobile) {
// I am connected to a mobile network. }
else if (connectivityResult == ConnectivityResult.wifi) {
// I am connected to a wifi network.
}

Answer 2

You can use connectivity_plus package to check internet connection. The http package that we use to call api can't tell if we don't have internet or the server is down.
class NetworkConnectivity {
NetworkConnectivity._();
static final _instance = NetworkConnectivity._();
static NetworkConnectivity get instance => _instance;
final _networkConnectivity = Connectivity();
final _controller = StreamController.broadcast();
Stream get myStream => _controller.stream;
// 1.
void initialise() async {
ConnectivityResult result = await _networkConnectivity.checkConnectivity();
_checkStatus(result);
_networkConnectivity.onConnectivityChanged.listen((result) {
print(result);
_checkStatus(result);
});
}
// 2.
void _checkStatus(ConnectivityResult result) async {
bool isOnline = false;
try {
final result = await InternetAddress.lookup('example.com');
isOnline = result.isNotEmpty && result[0].rawAddress.isNotEmpty;
} on SocketException catch (_) {
isOnline = false;
}
_controller.sink.add({result: isOnline});
}
void disposeStream() => _controller.close();
}
You can use the following guide: Flutter Internet Connectivity