Wifi Connect-Disconnect Listener

Question

Which listener does my class have to implement inorder to automatically check code if the wifi connects/disconnects?

I'm able to manually check for wifi connection/disconnection but each time I need to connect/disconnect WIFI from android settings and then run my program for the result.

My current code is as simple as:

WifiManager wifi = (WifiManager)getSystemService(Context.WIFI_SERVICE);
if (wifi.isWifiEnabled()==true)
{
    tv.setText("You are connected");
}
else
{
    tv.setText("You are NOT connected");
}

Answer 1

Actually you're checking for whether Wi-Fi is enabled, that doesn't necessarily mean that it's connected. It just means that Wi-Fi mode on the phone is enabled and able to connect to Wi-Fi networks.

This is how I'm listening for actual Wi-Fi connections in my Broadcast Receiver:

public class WifiReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {     
        ConnectivityManager conMan = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); 
        NetworkInfo netInfo = conMan.getActiveNetworkInfo();
        if (netInfo != null && netInfo.getType() == ConnectivityManager.TYPE_WIFI) 
            Log.d("WifiReceiver", "Have Wifi Connection");
        else
            Log.d("WifiReceiver", "Don't have Wifi Connection");    
    }   
};

In order to access the active network info you need to add the following uses-permission to your AndroidManifest.xml:

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

And the following intent receiver (or you could add this programmatically...)

<!-- Receive Wi-Fi connection state changes -->
<receiver android:name=".WifiReceiver">
    <intent-filter>
        <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
    </intent-filter>
</receiver>

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EDIT: In Lollipop, Job Scheduling may help if you're looking to perform an action when the user connects to an unmetered network connection. Take a look: http://developer.android.com/about/versions/android-5.0.html#Power

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EDIT 2: Another consideration is that my answer doesn't check that you have a connection to the internet. You could be connected to a Wi-Fi network which requires you to sign in. Here's a useful "IsOnline()" check: https://stackoverflow.com/a/27312494/1140744