CONNECTIVITY_ACTION intent received twice when Wifi connected

This is the proper way to register for connectivity changes on API 21 and higher. The following code can be placed in a base activity and that way you can expect every screen in your app (that inherits from this activity) to get these callbacks.

First, create a network callback which will monitor connectivity changes.

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private val networkCallback: ConnectivityManager.NetworkCallback = object : ConnectivityManager.NetworkCallback() {

    // Implement the callback methods that are relevant to the actions you want to take.
    // I have implemented onAvailable for connecting and onLost for disconnecting.

    override fun onAvailable(network: Network?) {
        super.onAvailable(network)
    }

    override fun onLost(network: Network?) {
        super.onLost(network)
    }
}

Then, register and unregister this callback in the relevant spots.

override fun onResume() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        val cm = getSystemService(Context.CONNECTIVITY_SERVICE) as? ConnectivityManager
        cm?.registerNetworkCallback(NetworkRequest.Builder().build(), networkCallback)
    }
}

And unregister when appropriate.

override fun onPause() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        val cm = getSystemService(Context.CONNECTIVITY_SERVICE) as? ConnectivityManager
        cm?.unregisterNetworkCallback(networkCallback)
    }
}

Notice that there is a check for Build.VERSION_CODES.LOLLIPOP. This functionality is only available in Lollipop and above. Be sure to have a plan for how to handle network status changes in Pre-Lollipop devices if you support less than API 21 in your app.

NOTE: For a recent, up-to-date answer, see this one below!

After a lot of googling and debugging, I believe this is the correct way to determine if Wifi has connected or disconnected.

The onReceive() method in the BroadcastReceiver:

public void onReceive(final Context context, final Intent intent) {

if(intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
    NetworkInfo networkInfo =
        intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
    if(networkInfo.isConnected()) {
        // Wifi is connected
        Log.d("Inetify", "Wifi is connected: " + String.valueOf(networkInfo));
    }
} else if(intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {
    NetworkInfo networkInfo =
        intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);
    if(networkInfo.getType() == ConnectivityManager.TYPE_WIFI &&
        ! networkInfo.isConnected()) {
        // Wifi is disconnected
        Log.d("Inetify", "Wifi is disconnected: " + String.valueOf(networkInfo));
    }
}
}

Together with the following receiver element in AndroidManifest.xml

<receiver android:name="ConnectivityActionReceiver"
    android:enabled="true" android:label="ConnectivityActionReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
        <action android:name="android.net.wifi.STATE_CHANGE"/>
    </intent-filter>
</receiver>

Some explanation:

• When only considering ConnectivityManager.CONNECTIVITY_ACTION, I always get two intents containing identical NetworkInfo instances (both getType() == TYPE_WIFI and isConnected() == true) when Wifi connects - the issue described in this question.

• When only using WifiManager.NETWORK_STATE_CHANGED_ACTION, there is no intent broadcasted when Wifi disconnects, but two intents containing different NetworkInfo instances, allowing to determine one event when Wifi is connected.

NOTE: I've received one single crash report (NPE) where the intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO) returned null. So, even if it seems to be extremely rare to happen, it might be a good idea to add a null check.

Cheers, Torsten

If you're listening on WifiManager.NETWORK_STATE_CHANGED_ACTION you'll receive this twice because there are 2 methods in the NetworkInfo

• isConnectedOrConnecting()
• isConnected()

First time isConnectedOrConnecting() returns true and isConnected() false
Second time isConnectedOrConnecting() and isConnected() return true

Cheers