Android event for internet connectivity state change [duplicate]

very old post but i would like to share my receiver

no need to put your hands on manifest or other boring resources :)

USAGE

YOUR ACTIVITY:

/*
 * You need to implement NetworkStateReceiverListener.
 * This interface is described inside the NewtworkStateReceiver class
 */
public class MyActivity implements NetworkStateReceiverListener {
    /* ... */
    private NetworkStateReceiver networkStateReceiver;
}

IN YOUR ACTIVITY: INSTANTIATE THE RECEIVER

public void onCreate(Bundle savedInstanceState) {
    /* ... */
    networkStateReceiver = new NetworkStateReceiver();
    networkStateReceiver.addListener(this);
    this.registerReceiver(networkStateReceiver, new IntentFilter(android.net.ConnectivityManager.CONNECTIVITY_ACTION));
}

public void onDestroy() {
    super.onDestroy();
    networkStateReceiver.removeListener(this);
    this.unregisterReceiver(networkStateReceiver);
}

IN YOUR ACTIVITY: IMPLEMENTS THE REQUIRED METHODS

@Override
public void networkAvailable() {
    Log.d("tommydevall", "I'm in, baby!");
    /* TODO: Your connection-oriented stuff here */
}

@Override
public void networkUnavailable() {
    Log.d("tommydevall", "I'm dancing with myself");
    /* TODO: Your disconnection-oriented stuff here */        
}

THE RECEIVER

just copy and paste into your project as NetworkStateReceiver.java

public class NetworkStateReceiver extends BroadcastReceiver {

    protected Set<NetworkStateReceiverListener> listeners;
    protected Boolean connected;

    public NetworkStateReceiver() {
        listeners = new HashSet<NetworkStateReceiverListener>();
        connected = null;
    }

    public void onReceive(Context context, Intent intent) {
        if(intent == null || intent.getExtras() == null)
            return;

        ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo ni = manager.getActiveNetworkInfo();

        if(ni != null && ni.getState() == NetworkInfo.State.CONNECTED) {
            connected = true;
        } else if(intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY,Boolean.FALSE)) {
            connected = false;
        }

        notifyStateToAll();
    }

    private void notifyStateToAll() {
        for(NetworkStateReceiverListener listener : listeners)
            notifyState(listener);
    }

    private void notifyState(NetworkStateReceiverListener listener) {
        if(connected == null || listener == null)
            return;

        if(connected == true)
            listener.networkAvailable();
        else
            listener.networkUnavailable();
    }

    public void addListener(NetworkStateReceiverListener l) {
        listeners.add(l);
        notifyState(l);
    }

    public void removeListener(NetworkStateReceiverListener l) {
        listeners.remove(l);
    }

    public interface NetworkStateReceiverListener {
        public void networkAvailable();
        public void networkUnavailable();
    }
}

ENJOY ;)

If you just want to do something simple when the connectivity changes, there is a much easier solution.

In your activity, create a Broadcast Receiver:

private BroadcastReceiver networkStateReceiver=new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        ConnectivityManager manager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo ni = manager.getActiveNetworkInfo();
        doSomethingOnNetworkChange(ni);
    }
};

Then in onResume and onPause do the registration:

@Override
public void onResume() {
    super.onResume();
    registerReceiver(networkStateReceiver, new IntentFilter(android.net.ConnectivityManager.CONNECTIVITY_ACTION));
}

@Override
public void onPause() {
    unregisterReceiver(networkStateReceiver);
    super.onPause();
}

Not quite sure what was going on in Tommaso's broadcast receiver but it wasn't working for me, here's my implementation. It only notifies on change between connectivity available/unavailable.

Also I register it in onResume() and unregister in onPause(). Otherwise it's the same as above.

public class NetworkStateReceiver extends BroadcastReceiver {

    private ConnectivityManager mManager;
    private List<NetworkStateReceiverListener> mListeners;
    private boolean mConnected;

    public NetworkStateReceiver(Context context) {
        mListeners = new ArrayList<NetworkStateReceiverListener>();
        mManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        checkStateChanged();
    }

    public void onReceive(Context context, Intent intent) {
        if (intent == null || intent.getExtras() == null)
            return;

        if (checkStateChanged()) notifyStateToAll();
    }

    private boolean checkStateChanged() {
        boolean prev = mConnected;
        NetworkInfo activeNetwork = mManager.getActiveNetworkInfo();
        mConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
        return prev != mConnected;
    }

    private void notifyStateToAll() {
        for (NetworkStateReceiverListener listener : mListeners) {
            notifyState(listener);
        }
    }

    private void notifyState(NetworkStateReceiverListener listener) {
        if (listener != null) {
            if (mConnected) listener.onNetworkAvailable();
            else listener.onNetworkUnavailable();
        }
    }

    public void addListener(NetworkStateReceiverListener l) {
        mListeners.add(l);
        notifyState(l);
    }

    public void removeListener(NetworkStateReceiverListener l) {
        mListeners.remove(l);
    }

    public interface NetworkStateReceiverListener {
        public void onNetworkAvailable();

        public void onNetworkUnavailable();
    }
}