Check whether there is an Internet connection available on Flutter app

Question

I have a network call to be executed  But before doing that I need to check whether the device have internet connectivity   This is what i have done so far     var connectivityResult   new Connectivity   checkConnectivity      User defined class     if  connectivityResult    ConnectivityResult mobile            connectivityResult    ConnectivityResult wifi          this getData          else         neverSatisfied            Above method is not working

User · Answer

Using   dependencies    connectivity   0 4 2   what we got from resouces is         import  package connectivity connectivity dart          Future lt bool gt  check   async           var connectivityResult   await  Connectivity   checkConnectivity             if  connectivityResult    ConnectivityResult mobile              return true            else if  connectivityResult    ConnectivityResult wifi              return true                    return false            Future is little problematic for me  we have to implement it every single time like    check   then  intenet          if  intenet    null  amp  amp  intenet               Internet Present Case                  No-Internet Case           So to solve this problem i have created a class Which accept a function with boolean isNetworkPresent parameter like this   methodName bool isNetworkPresent      And the Utility Class is    import  package connectivity connectivity dart    class NetworkCheck     Future lt bool gt  check   async       var connectivityResult   await  Connectivity   checkConnectivity         if  connectivityResult    ConnectivityResult mobile          return true        else if  connectivityResult    ConnectivityResult wifi          return true            return false         dynamic checkInternet Function func        check   then  intenet          if  intenet    null  amp  amp  intenet            func true                 else      func false                        And to use connectivity-check utilty    fetchPrefrence bool isNetworkPresent        if isNetworkPresent         else               i will use this syntax   NetworkCheck networkCheck   new NetworkCheck    networkCheck checkInternet fetchPrefrence

User · Answer

Full example demonstrating a listener of the internet connectivity and its source    Credit to   connectivity and G  nter Z  chbauer  import  dart async   import  dart io   import  package connectivity connectivity dart   import  package flutter material dart    void main     gt  runApp MaterialApp home  HomePage       class HomePage extends StatefulWidget      override    HomePageState createState     gt   HomePageState       class  HomePageState extends State lt HomePage gt      Map  source    ConnectivityResult none  false     MyConnectivity  connectivity   MyConnectivity instance      override   void initState         super initState         connectivity initialise         connectivity myStream listen  source          setState      gt   source   source                   override   Widget build BuildContext context        String string      switch   source keys toList   0           case ConnectivityResult none          string    Offline           break        case ConnectivityResult mobile          string    Mobile  Online           break        case ConnectivityResult wifi          string    WiFi  Online              return Scaffold        appBar  AppBar title  Text  Internet           body  Center child  Text   string   style  TextStyle fontSize  36                    override   void dispose          connectivity disposeStream        super dispose           class MyConnectivity     MyConnectivity  internal       static final MyConnectivity  instance   MyConnectivity  internal       static MyConnectivity get instance   gt   instance     Connectivity connectivity   Connectivity       StreamController controller   StreamController broadcast       Stream get myStream   gt  controller stream     void initialise   async       ConnectivityResult result   await connectivity checkConnectivity         checkStatus result       connectivity onConnectivityChanged listen  result           checkStatus result                  void  checkStatus ConnectivityResult result  async       bool isOnline   false      try         final result   await InternetAddress lookup  example com          if  result isNotEmpty  amp  amp  result 0  rawAddress isNotEmpty            isOnline   true          else         isOnline   false        on SocketException catch             isOnline   false            controller sink add  result  isOnline           void disposeStream     gt  controller close

User · Answer

I having some problem with the accepted answer  but it seems it solve answer for others  I would like a solution that can get a response from the url it uses  so I thought http would be great for that functionality  and for that I found this answer really helpful  How do I check Internet Connectivity using HTTP requests Flutter Dart

User · Answer

Following  dennmatt  s answer  I noticed that InternetAddress lookup may return successful results even if the internet connection is off - I tested it by connecting from my simulator to my home WiFi  and then disconnecting my router s cable  I think the reason is that the router caches the domain-lookup results so it does not have to query the DNS servers on each lookup request   Anyways  if you use Firestore like me  you can replace the try-SocketException-catch block with an empty transaction and catch TimeoutExceptions   try     await Firestore instance runTransaction  Transaction tx      timeout Duration seconds  5      hasConnection   true    on PlatformException catch         May be thrown on Airplane mode   hasConnection   false    on TimeoutException catch        hasConnection   false      Also  please notice that previousConnection is set before the async intenet-check  so theoretically if checkConnection   is called multiple times in a short time  there could be multiple hasConnection true in a row or multiple hasConnection false in a row  I m not sure if  dennmatt did it on purpose or not  but in our use-case there were no side effects  setState was only called twice with the same value

User · Answer

I made a base class for widget state  Usage instead of State lt LoginPage gt  use BaseState lt LoginPage gt   then just use the boolean variable isOnline  Text isOnline    is Online     is Offline     First  add connectivity plugin   dependencies    connectivity   0 4 3 2   Then add the BaseState class  import  dart async   import  dart io   import  package flutter services dart    import  package connectivity connectivity dart   import  package flutter widgets dart        a base class for any statful widget for checking internet connectivity abstract class BaseState lt T extends StatefulWidget gt  extends State      void castStatefulWidget       final Connectivity  connectivity   Connectivity       StreamSubscription lt ConnectivityResult gt   connectivitySubscription         the internet connectivity status   bool isOnline   true         initialize connectivity checking       Platform messages are asynchronous  so we initialize in an async method    Future lt void gt  initConnectivity   async          Platform messages may fail  so we use a try catch PlatformException      try         await  connectivity checkConnectivity          on PlatformException catch  e          print e toString                   If the widget was removed from the tree while the asynchronous platform        message was in flight  we want to discard the reply rather than calling        setState to update our non-existent appearance      if   mounted          return             await  updateConnectionStatus   then  bool isConnected    gt  setState                isOnline   isConnected                       override   void initState         super initState        initConnectivity         connectivitySubscription   Connectivity            onConnectivityChanged          listen  ConnectivityResult result  async         await  updateConnectionStatus   then  bool isConnected    gt  setState                  isOnline   isConnected                                 override   void dispose          connectivitySubscription cancel        super dispose           Future lt bool gt   updateConnectionStatus   async       bool isConnected      try         final List lt InternetAddress gt  result             await InternetAddress lookup  google com          if  result isNotEmpty  amp  amp  result 0  rawAddress isNotEmpty            isConnected   true                on SocketException catch             isConnected   false        return false            return isConnected          And you need to cast the widget in your state like this   override   void castStatefulWidget            ignore  unnecessary statements     widget is StudentBoardingPage

User · Answer

late answer  but use this package to to check  Package Name  data connection checker  in you pubspec yuml file   dependencies      data connection checker   0 3 4   create a file called connection dart or any name you want  import the package   import  package data connection checker data connection checker dart     check if there is internet connection or not   print await DataConnectionChecker   hasConnection

User · Answer

For anyone else who lands here I d like to add on to G  nter Z  chbauer s answer this was my solution for implementing a utility to know if there s internet or not regardless of anything else   Disclaimer   I m new to both Dart and Flutter so this may not be the best approach  but would love to get feedback     Combining flutter connectivity and G  nter Z  chbauer s connection test  My requirements  I didn t want to have a bunch of repeated code anywhere I needed to check the connection and I wanted it to automatically update components or anything else that cared about the connection whenever there was a change   ConnectionStatusSingleton  First we setup a Singleton  If you re unfamiliar with this pattern there s a lot of good info online about them  But the gist is that you want to make a single instance of a class during the application life cycle and be able to use it anywhere   This singleton hooks into flutter connectivity and listens for connectivity changes  then tests the network connection  then uses a StreamController to update anything that cares   It looks like this   import  dart io     InternetAddress utility import  dart async     For StreamController Stream  import  package connectivity connectivity dart    class ConnectionStatusSingleton         This creates the single instance by calling the   internal  constructor specified below     static final ConnectionStatusSingleton  singleton   new ConnectionStatusSingleton  internal        ConnectionStatusSingleton  internal           This is what s used to retrieve the instance through the app     static ConnectionStatusSingleton getInstance     gt   singleton         This tracks the current connection status     bool hasConnection   false         This is how we ll allow subscribing to connection changes     StreamController connectionChangeController   new StreamController broadcast           flutter connectivity     final Connectivity  connectivity   Connectivity           Hook into flutter connectivity s Stream to listen for changes       And check the connection status out of the gate     void initialize              connectivity onConnectivityChanged listen  connectionChange           checkConnection               Stream get connectionChange   gt  connectionChangeController stream         A clean up method to close our StreamController          Because this is meant to exist through the entire application life cycle this isn t          really an issue     void dispose             connectionChangeController close                 flutter connectivity s listener     void  connectionChange ConnectivityResult result            checkConnection                 The test to actually see if there is a connection     Future lt bool gt  checkConnection   async           bool previousConnection   hasConnection           try               final result   await InternetAddress lookup  google com                if  result isNotEmpty  amp  amp  result 0  rawAddress isNotEmpty                    hasConnection   true                else                   hasConnection   false                          on SocketException catch                  hasConnection   false                       The connection status changed send out an update to all listeners         if  previousConnection    hasConnection                connectionChangeController add hasConnection                      return hasConnection            Usage  Initialization  First we have to make sure we call the initialize of our singleton  But only once  This parts up to you but I did it in my app s main     void main         ConnectionStatusSingleton connectionStatus   ConnectionStatusSingleton getInstance        connectionStatus initialize         runApp MyApp            Call this if initialization is occuring in a scope that will end during app lifecycle       connectionStatus dispose           In Widget or elsewhere  import  dart async     For StreamSubscription       class MyWidgetState extends State lt MyWidget gt        StreamSubscription  connectionChangeStream       bool isOffline   false        override     initState             super initState             ConnectionStatusSingleton connectionStatus   ConnectionStatusSingleton getInstance             connectionChangeStream   connectionStatus connectionChange listen connectionChanged              void connectionChanged dynamic hasConnection            setState                  isOffline    hasConnection                          override     Widget build BuildContext ctxt                          Hope somebody else finds this useful     Example github repo  https   github com dennmat flutter-connectiontest-example  Toggle airplane mode in the emulator to see the result

User · Answer

I used the data connection checker package to check the internet access even if the connection available by wifi or mobile  it works well  here is the code to check the connection  bool result   await DataConnectionChecker   hasConnection  if result    true       print  YAY  Free cute dog pics       else      print  No internet    Reason        print DataConnectionChecker   lastTryResults      head over the package if you want more information  Data Connection Checker Package

User · Answer

I ve created a package that  I think  deals reliably with this issue   The package on pub dev  The package on GitHub  Discussion is very welcome  You can use the issues tracker on GitHub     I no longer think this below is a reliable method     Wanna add something to  Oren s answer  you should really add one more catch  which will catch all other exceptions  just to be safe   OR just remove the exception type altogether and use a catch  that deals with all of the exceptions   Case 1   try     await Firestore instance      runTransaction  Transaction tx           timeout Duration seconds  5      hasConnection   true    on PlatformException catch         May be thrown on Airplane mode   hasConnection   false    on TimeoutException catch        hasConnection   false    catch         hasConnection   false      or even simpler     Case 2    try     await Firestore instance      runTransaction  Transaction tx           timeout Duration seconds  5      hasConnection   true    catch         hasConnection   false

User · Answer

The connectivity plugin states in its docs that it only provides information if there is a network connection  but not if the network is connected to the Internet     Note that on Android  this does not guarantee connection to Internet  For instance  the app might have wifi access but it might be a VPN or a hotel WiFi with no access    You can use   import  dart io       try     final result   await InternetAddress lookup  google com      if  result isNotEmpty  amp  amp  result 0  rawAddress isNotEmpty        print  connected          on SocketException catch         print  not connected

User · Answer

I had an issue with the proposed solutions  using lookup does not always return the expected value  This is due to DNS caching  the value of the call is cached and intead of doing a proper call on the next try it gives back the cached value  Of course this is an issue here as it means if you lose connectivity and call lookup it could still return the cached value as if you had internet  and conversely  if you reconnect your internet after lookup returned null it will still return null for the duration of the cache  which can be a few minutes  even if you do have internet now  TL DR  lookup returning something does not necessarily mean you have internet  and it not returning anything does not necessarily mean you don t have internet  It is not reliable  I implemented the following solution by taking inspiration from the data connection checker plugin       If any of the pings returns true then you have internet  for sure   If none do  you probably don t    Future lt bool gt   checkInternetAccess             We use a mix of IPV4 and IPV6 here in case some networks only accept one of the types          Only tested with an IPV4 only network so far  I don t have access to an IPV6 network       final List lt InternetAddress gt  dnss           InternetAddress  8 8 8 8   type  InternetAddressType IPv4      Google       InternetAddress  2001 4860 4860  8888   type  InternetAddressType IPv6      Google       InternetAddress  1 1 1 1   type  InternetAddressType IPv4      CloudFlare       InternetAddress  2606 4700 4700  1111   type  InternetAddressType IPv6      CloudFlare       InternetAddress  208 67 222 222   type  InternetAddressType IPv4      OpenDNS       InternetAddress  2620 0 ccc  2   type  InternetAddressType IPv6      OpenDNS       InternetAddress  180 76 76 76   type  InternetAddressType IPv4      Baidu       InternetAddress  2400 da00  6666   type  InternetAddressType IPv6      Baidu             final Completer lt bool gt  completer   Completer lt bool gt          int callsReturned   0      void onCallReturned bool isAlive          if  completer isCompleted  return         if  isAlive            completer complete true           else           callsReturned            if  callsReturned  gt   dnss length              completer complete false                                dnss forEach  dns    gt   pingDns dns  then onCallReturned         return completer future         Future lt bool gt   pingDns InternetAddress dnsAddress  async       const int dnsPort   53      const Duration timeout   Duration seconds  3        Socket socket      try         socket   await Socket connect dnsAddress  dnsPort  timeout  timeout         socket  destroy          return true        on SocketException         socket  destroy              return false       The call to  checkInternetAccess takes at most a duration of timeout to complete  3 seconds here   and if we can reach any of the DNS it will complete as soon as the first one is reached  without waiting for the others  as reaching one is enough to know you have internet   All the calls to  pingDns are done in parallel  It seems to work well on an IPV4 network  and when I can t test it on an IPV6 network  I don t have access to one  I think it should still work  It also works on release mode builds  but I yet have to submit my app to Apple to see if they find any issue with this solution  It should also work in most countries  including China   if it does not work in one you can add a DNS to the list that is accessible from your target country

User · Answer

Just trying to simplify the code using Connectivity Package in Flutter   import  package connectivity connectivity 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    else        I am not connected to the internet

User · Answer

Here Is My Solution It Checks Internet Connectivity as well as Data Connection I hope You Like it   First of all add dependencies in your pubsec yaml  dependencies              data connection checker    And Here Is The main dart Of My Solution  import  dart async    import  package data connection checker data connection checker dart   import  package flutter material dart    void main     gt  runApp MyApp      class MyApp extends StatelessWidget      override   Widget build BuildContext context        return MaterialApp        title   Data Connection Checker         home  HomePage                  class HomePage extends StatefulWidget      override    HomePageState createState     gt   HomePageState       class  HomePageState extends State lt HomePage gt      StreamSubscription lt DataConnectionStatus gt  listener     var Internetstatus    Unknown       override   void initState            TODO  implement initState     super initState           updateConnectionStatus          CheckInternet            override   void dispose            TODO  implement dispose     listener cancel        super dispose           CheckInternet   async          Simple check to see if we have internet     print  The statement  this machine is connected to the Internet  is          print await DataConnectionChecker   hasConnection          returns a bool         We can also get an enum instead of a bool     print  Current status    await DataConnectionChecker   connectionStatus            prints either DataConnectionStatus connected        or DataConnectionStatus disconnected         This returns the last results from the last call        to either hasConnection or connectionStatus     print  Last results    DataConnectionChecker   lastTryResults             actively listen for status updates     listener   DataConnectionChecker   onStatusChange listen  status          switch  status            case DataConnectionStatus connected            Internetstatus  Connectd TO THe Internet             print  Data connection is available               setState                               break          case DataConnectionStatus disconnected            Internetstatus  No Data Connection             print  You are disconnected from the internet               setState                               break                          close listener after 30 seconds  so the program doesn t run forever       await Future delayed Duration seconds  30          await listener cancel        return await await DataConnectionChecker   connectionStatus          override   Widget build BuildContext context        return Scaffold        appBar  AppBar          title  Text  Data Connection Checker                   body  Container          child  Center            child  Text   Internetstatus

User · Answer

I ultimately  though reluctantly  settled on the solution given by  abernee in a previous answer to this question  I always try and use as few external packages in my projects as possible - as I know external packages are the only   potential   points of failure in the software I create  So to link to TWO external packages just for a simple implementation like this was not easy for me  Nevertheless  I took abernee s code and modified it to make it leaner and more sensible  By sensible I mean he consumes the power of the Connectivity package in his function but then wastes it internally by not returning the most valuable outputs from this package   i e  the network identification    So here is the modified version of abernee s solution  import  package connectivity connectivity dart   import  package data connection checker data connection checker dart         McGyver  - the ultimate cool guy  the best helper class any app can ask for   class McGyver      static Future lt Map lt String  dynamic gt  gt  checkInternetAccess   async                                                                                                                    INFO  ONLY TWO return TYPES for Map  dynamic  value   gt   lt bool gt  and  lt ConnectivityResult gt                                                                                                                   Map lt String  dynamic gt  mapCon      final String isConn    isConnected   netType    networkType       ConnectivityResult conRes   await  Connectivity   checkConnectivity         switch  conRes          case ConnectivityResult wifi        WiFi Network  true            if  await DataConnectionChecker   hasConnection          Internet Access  true              mapCon   Map unmodifiable  isConn  true  netType  ConnectivityResult wifi              else             mapCon   Map unmodifiable  isConn  false  netType  ConnectivityResult wifi                      break        case ConnectivityResult mobile        Mobile Network  true            if  await DataConnectionChecker   hasConnection          Internet Access  true              mapCon   Map unmodifiable  isConn  true  netType  ConnectivityResult mobile              else             mapCon   Map unmodifiable  isConn  false  netType  ConnectivityResult mobile                      break        case ConnectivityResult none        No Network  true            mapCon   Map unmodifiable  isConn  false  netType  ConnectivityResult none            break            return mapCon           Then you d use this static function via a simple call from anywhere in your code as follows  bool isConn  ConnectivityResult netType  McGyver checkInternetAccess   then     mapCIA          mapCIA     amalgamation for  map  from  CheckInternetAccess  function result      debugPrint  quot  mapCIA  Keys    mapCIA keys  quot        isConn   mapCIA  isConnected        netType   mapCIA  networkType           debugPrint  quot Internet Access   isConn       Network Type   netType quot      It s a pity that you have to link to TWO EXTERNAL PACKAGES to get this very basic functionality in your Flutter project - but I guess for now this is the best we have  I actually prefer the Data Connection Checker package over the Connectivity package - but  at the time of posting this  the former was missing that very important network identification feature that I require from the Connectivity package  This is the reason I defaulted onto this approach   temporarily

User · Answer

I found that just using the connectivity package was not enough to tell if the internet was available or not   In Android it only checks if there is WIFI or if mobile data is turned on  it does not check for an actual internet connection    During my testing  even with no mobile signal ConnectivityResult mobile would return true  With IOS my testing found that the connectivity plugin does correctly detect if there is an internet connection when the phone has no signal  the issue was only with Android  The solution I found was to use the data connection checker package along with the connectivity package   This just makes sure there is an internet connection by making requests to a few reliable addresses  the default timeout for the check is around 10 seconds  My finished isInternet function looked a bit like this    Future lt bool gt  isInternet   async       var connectivityResult   await  Connectivity   checkConnectivity         if  connectivityResult    ConnectivityResult mobile             I am connected to a mobile network  make sure there is actually a net connection        if  await DataConnectionChecker   hasConnection               Mobile data detected  amp  internet connection confirmed          return true          else              Mobile data detected but no internet connection found          return false                else if  connectivityResult    ConnectivityResult wifi             I am connected to a WIFI network  make sure there is actually a net connection        if  await DataConnectionChecker   hasConnection               Wifi detected  amp  internet connection confirmed          return true          else              Wifi detected but no internet connection found          return false                else            Neither mobile data or WIFI detected  not internet connection found        return false             The if  await DataConnectionChecker   hasConnection  part is the same for both mobile and wifi connections and should probably be moved to a separate function   I ve not done that here to leave it more readable  This is my first Stack Overflow answer  hope it helps someone

User · Answer

The connectivity  package does not guarantee the actual internet connection  could be just wifi connection without internet access    Quote from the documentation      Note that on Android  this does not guarantee connection to Internet  For instance  the app might have wifi access but it might be a VPN or a hotel WiFi with no access    If you really need to check the connection to the www Internet the better choice would be  data connection checker package

[flutter] Check whether there is an Internet connection available on Flutter app

Examples related to flutter

Examples related to dart

Examples related to flutter-plugin