android - Using a WiFi without Internet Connection

Question

In my app I am connecting to a device that has it's own WiFi network. In android 6 and above the system asks me after a few seconds if I want to connect to this network even though there is no internet connection. Only after approving that message I can connect to my device. I tried connecting to the network programmatically and not force the user to go to his settings and connect manually every time. I used the following code to connect to the devices network:

private void connectToWiFi(WifiManager wifiManager, String wifiName) {

    WifiConfiguration configuration = new WifiConfiguration();
    configuration.SSID = """ + wifiName + """;
    configuration.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
    wifiManager.addNetwork(configuration);
    List<WifiConfiguration> list = wifiManager.getConfiguredNetworks();
    for (WifiConfiguration i : list) {
        if (i.SSID != null && i.SSID.equals(""" + wifiName + """)) {
            wifiManager.disconnect();
            wifiManager.enableNetwork(i.networkId, true);
            wifiManager.reconnect();
            break;
        }
    }
}

and also trying to force the app to use the WiFi connection and not the cellular data I am using :

NetworkRequest.Builder builder;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        builder = new NetworkRequest.Builder();
        builder.addTransportType(NetworkCapabilities.TRANSPORT_WIFI);

        connectivityManager.requestNetwork(builder.build(), new ConnectivityManager.NetworkCallback() {
            @Override
            public void onAvailable(Network network) {
                String ssid = wifiManager.getConnectionInfo().getSSID();
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    connectivityManager.bindProcessToNetwork(null);
                    if (ssid.equals(""" + Prefs.getWifiName(PUFMainActivity.this) + """)) {
                        connectivityManager.bindProcessToNetwork(network);
                        connectivityManager.unregisterNetworkCallback(this);
                    }
                }
            }
        });

    }

Although as long as the Cellular data is active the device doesn't apear to be connected. If I disable the Cellular data then it works fine. I need to know if there is a way to do what I want programmatically without telling the user to disable his Cellular data.

Thanks

Answer 1

Although as long as the Cellular data is active the device doesn't apear to be connected. If I disable the Cellular data then it works fine.

I was facing a similar problem. The default solution didn't work for me so I used the bindSocket method from Network class, and apparently it is working just fine. I don't know if this solution applies to your problem, but here's some code:

ConnectivityManager connectivityManager = (ConnectivityManager) context.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
Network[] networks = connectivityManager.getAllNetworks();
for(Network network : networks){
   NetworkInfo networkInfo = connectivityManager.getNetworkInfo(network);

   if(networkInfo.getType() == ConnectivityManager.TYPE_WIFI){
       wifiNetwork = network; // Grabbing the Network object for later usage
   }
}

and after the socket:

if(android.os.Build.VERSION.SDK_INT >= 22) {
   wifiNetwork.bindSocket(socket);
}

UPDATE: You can use a NetworkCallback to grab the Network object as well.

NetworkRequest.Builder builder;
builder = new NetworkRequest.Builder();
builder.addTransportType(NetworkCapabilities.TRANSPORT_WIFI);
ConnectivityManager connectivityManager = (ConnectivityManager) context.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
connectivityManager.requestNetwork(builder.build(), new ConnectivityManager.NetworkCallback() {
   @Override
   public void onAvailable(Network network) {
      wifiNetwork = network;
   }
});