How can I receive a notification when the device loses network connectivity in android L (API 21)

Question

I\'m using this code to be notified when the connection is lost in API 20 and down.

registerReceiver(getConnectivityStateBroadcastReceiver(), new IntentFilte         


        

Answer 1

OK, so I figure out how to do it but would appreciate confirmation that this solution is the right one.

All I did is add a call to this code in the onCreate of my application class

/**
 *
 */
@SuppressLint("NewApi")
private void registerConnectivityNetworkMonitorForAPI21AndUp() {

    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
        return;
    }

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

    NetworkRequest.Builder builder = new NetworkRequest.Builder();

    connectivityManager.registerNetworkCallback(
            builder.build(),
            new ConnectivityManager.NetworkCallback() {
                /**
                 * @param network
                 */
                @Override
                public void onAvailable(Network network) {

                    sendBroadcast(
                            getConnectivityIntent(false)
                    );

                }

                /**
                 * @param network
                 */
                @Override
                public void onLost(Network network) {

                    sendBroadcast(
                            getConnectivityIntent(true)
                    );

                }
            }

    );

}

 /**
 * @param noConnection
 * @return
 */
private Intent getConnectivityIntent(boolean noConnection) {

    Intent intent = new Intent();

    intent.setAction("mypackage.CONNECTIVITY_CHANGE");
    intent.putExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, noConnection);

    return intent;

}

and in the IntentFilter that already monitoring my connectivity for API 20 and less I added this

IntentFilter filter = new IntentFilter();

filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
filter.addAction("mypackage.CONNECTIVITY_CHANGE");

and now my already working broadcast receiver get notification about network changes in API 21 too.

Answer 2

I'll paste my complete solution since I needed to look into many places in order to make it work:

In Application class

public void onCreate(){
...

IntentFilter filter = new IntentFilter();
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        Timber.d("using registerNetworkCallback");
        createChangeConnectivityMonitor();
        filter.addAction(MY_CONNECTIVITY_CHANGE);
    } else {
        Timber.d("using old broadcast receiver");
        filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
    }

    registerReceiver(new SyncOnConnectivityReceiver(), filter);
 }

  @RequiresApi(Build.VERSION_CODES.N)
   private void createChangeConnectivityMonitor() {
    final Intent intent = new Intent(MY_CONNECTIVITY_CHANGE);
    ConnectivityManager connectivityManager = (ConnectivityManager) 
  getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivityManager != null) {
        connectivityManager.registerNetworkCallback(
               new NetworkRequest.Builder().build(), 
               new ConnectivityManager.NetworkCallback() {
                    /**
                     * @param network
                     */
                    @Override
                    public void onAvailable(Network network) {
                        Timber.d("On available network");
                        sendBroadcast(intent);
                    }

                    /**
                     * @param network
                     */
                    @Override
                    public void onLost(Network network) {
                        Timber.d("On not available network");
                        sendBroadcast(intent);
                    }
                });
    }

}

In my receiver:

public class SyncOnConnectivityReceiver extends BroadcastReceiver {

@Override
 public void onReceive(@Nullable final Context context, Intent intent) {
    Timber.d("triggering on connectivity change");
    if (context != null && isNetworkAvailable(context)) {
        Executors.newSingleThreadExecutor().submit(new Runnable() {
            @Override
            public void run() {
                syncBusData(context);
            }
        });
    }
}

private boolean isNetworkAvailable(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (cm != null) {
        NetworkInfo networkInfo = cm.getActiveNetworkInfo();
        return networkInfo != null && networkInfo.isConnected();
    }
    return false;
}

private void syncData(Context context) {

}
}

In AndroidManifiest.xml

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<receiver android:name="com.innofied.viapool.location.SyncOnConnectivityReceiver"/>

Answer 3

Try this if you need

• register to the network state changes
• consider all network interfaces
• want to be notified if network is available for any interface
• that code supports API>20 (you can add also legacy API support easily)

Declare the necessary variables in your class:

private static final HashMap<Network, Boolean> mNetworkStates = new HashMap<>();
private final Object mSyncNetworkState = new Object();
private Boolean mNetworkState;

Define your method which monitors the interface changes. mNetworkState shows always if at least one network interface is connected.

private void registerNetworkStateInfo(@NonNull final Context context) throws Exception {
    final ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkRequest.Builder builder = new NetworkRequest.Builder();

    if (connectivityManager != null) {
        connectivityManager.registerNetworkCallback(
                builder.build(),
                new ConnectivityManager.NetworkCallback() {
                    @Override
                    public void onAvailable(@NonNull Network network) {
                        mNetworkStates.put(network, true);
                        synchronized (mSyncNetworkState){
                            mNetworkState = true;
                        }

                        Log.d("Network state", "Network state: true");
                    }

                    @Override
                    public void onLost(@NonNull Network network) {
                        mNetworkStates.put(network, false);
                        synchronized (mSyncNetworkState){
                            mNetworkState = false;
                            Log.d("Network state", "Network state: false");

                            mNetworkStates.forEach(new BiConsumer<Network, Boolean>() {
                                @Override
                                public void accept(Network nextNetwork, Boolean state) {
                                    if (state.equals(true)) {
                                        mNetworkState= true;
                                        Log.d("Network state", "Network state: but true");
                                    }
                                }
                            });
                        }
                    }
                }
        );
    } else {
        synchronized (mSyncNetworkState){
            mNetworkState = false;
        }
        throw new Exception("Connectivity Manager is not available");
    }
}

Use your mNetworkState

synchronized (mSyncNetworkState){
    if (!mNetworkState) {
        throw new Exception("No network available");
    }
}