[java] Android: Internet connectivity change listener

I already have this code which listens to connectivity change -

public class NetworkStateReceiver extends BroadcastReceiver
{
  public void onReceive(Context context, Intent intent)
  {
    Log.d("app","Network connectivity change");

    if(intent.getExtras() != null)
    {
      NetworkInfo ni = (NetworkInfo) intent.getExtras().get(ConnectivityManager.EXTRA_NETWORK_INFO);
      if(ni != null && ni.getState() == NetworkInfo.State.CONNECTED)
      {
        Log.i("app", "Network " + ni.getTypeName() + " connected");
      }
    }

    if(intent.getExtras().getBoolean(ConnectivityManager.EXTRA_NO_CONNECTIVITY, Boolean.FALSE))
    {
      Log.d("app", "There's no network connectivity");
    }
  }
}

And I check Internet connectivity using this code - Internet Check

But the problem is that if network suddenly loses internet connection without any connectivity change, this code is useless. Is there any way to create Broadcast Receiver listener for Internet connectivity change? I have a web app and sudden Internet connectivity changes can cause problems.

Here's the Java code using registerDefaultNetworkCallback (and registerNetworkCallback for API < 24):

ConnectivityManager.NetworkCallback networkCallback = new ConnectivityManager.NetworkCallback() {
    @Override
    public void onAvailable(Network network) {
        // network available
    }

    @Override
    public void onLost(Network network) {
        // network unavailable
    }
};

ConnectivityManager connectivityManager =
        (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
    connectivityManager.registerDefaultNetworkCallback(networkCallback);
} else {
    NetworkRequest request = new NetworkRequest.Builder()
            .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET).build();
    connectivityManager.registerNetworkCallback(request, networkCallback);
}

Update:

Apps targeting Android 7.0 (API level 24) and higher do not receive CONNECTIVITY_ACTION broadcasts if they declare the broadcast receiver in their manifest. Apps will still receive CONNECTIVITY_ACTION broadcasts if they register their BroadcastReceiver with Context.registerReceiver() and that context is still valid.

You need to register the receiver via registerReceiver() method:

 IntentFilter intentFilter = new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE");
 mCtx.registerReceiver(new NetworkBroadcastReceiver(), intentFilter);

This should work:

public class ConnectivityChangeActivity extends Activity {

    private BroadcastReceiver networkChangeReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            Log.d("app","Network connectivity change");
        }
    };

    @Override
    protected void onResume() {
        super.onResume();

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        registerReceiver(networkChangeReceiver, intentFilter);
    }

    @Override
    protected void onPause() {
        super.onPause();

        unregisterReceiver(networkChangeReceiver);
    }
}

This my implementation which you can providing in application scope:

class NetworkStateHelper @Inject constructor(
        private val context: Context
) {
    private val cache: BehaviorSubject<Boolean> = BehaviorSubject.create()

    private val receiver = object : BroadcastReceiver() {
        override fun onReceive(c: Context?, intent: Intent?) {
            cache.onNext(isOnlineOrConnecting())
        }
    }

    init {
        val intentFilter = IntentFilter()
        intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION)
        context.registerReceiver(receiver, intentFilter)
        cache.onNext(isOnlineOrConnecting())
    }

    fun subscribe(): Observable<Boolean> {
        return cache
    }

    fun isOnlineOrConnecting(): Boolean {
        val cm = context.applicationContext.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        val netInfo = cm.activeNetworkInfo
        return netInfo != null && netInfo.isConnectedOrConnecting
    }
}

I used this rxjava and dagger2 libraies

ConnectivityAction is deprecated in api 28+. Instead you can use registerDefaultNetworkCallback as long as you support api 24+.

In Kotlin:

val connectivityManager = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
connectivityManager?.let {
    it.registerDefaultNetworkCallback(object : ConnectivityManager.NetworkCallback() {
        override fun onAvailable(network: Network) {
            //take action when network connection is gained
        }
        override fun onLost(network: Network?) {
            //take action when network connection is lost
        }
    })
}

I have noticed that no one mentioned WorkManger solution which is better and support most of android devices.

You should have a Worker with network constraint AND it will fired only if network available, i.e:

val constraints = Constraints.Builder().setRequiredNetworkType(NetworkType.CONNECTED).build()
val worker = OneTimeWorkRequestBuilder<MyWorker>().setConstraints(constraints).build()

And in worker you do whatever you want once connection back, you may fire the worker periodically .

i.e:

inside dowork() callback:

notifierLiveData.postValue(info)

1. first add dependency in your code as implementation 'com.treebo:internetavailabilitychecker:1.0.4'
2. implements your class with InternetConnectivityListener.

public class MainActivity extends AppCompatActivity implements InternetConnectivityListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        InternetAvailabilityChecker.init(this);
        mInternetAvailabilityChecker = InternetAvailabilityChecker.getInstance();
        mInternetAvailabilityChecker.addInternetConnectivityListener(this);
    }

    @Override
    public void onInternetConnectivityChanged(boolean isConnected) {
        if (isConnected) {
            alertDialog = new AlertDialog.Builder(this).create();
            alertDialog.setTitle(" internet is connected or not");
            alertDialog.setMessage("connected");
            alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                        }
                    });
            alertDialog.show();

    }
    else {
            alertDialog = new AlertDialog.Builder(this).create();
            alertDialog.setTitle("internet is connected or not");
            alertDialog.setMessage("not connected");
            alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                        }
                    });
            alertDialog.show();

        }
    }
}

implementation 'com.treebo:internetavailabilitychecker:1.0.1'

public class MyApp extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        InternetAvailabilityChecker.init(this);
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        InternetAvailabilityChecker.getInstance().removeAllInternetConnectivityChangeListeners();
    }
}