Internet listener Android example

Create one Broadcast Receiver for that and register it in manifest file.

First create a new class NetworkStateReceiver and extend BroadcastReceiver.

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");
     }
   }
}

Put this code in your AndroidManifest.xml under the “application” element:

<receiver android:name=".NetworkStateReceiver">
   <intent-filter>
      <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
   </intent-filter>
</receiver>

And add this permission

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

EDIT

This code just detects connectivity change but cannot tell whether the network it is connected to has a internet access. Use this method to check that –

public static boolean hasActiveInternetConnection(Context context) {
    if (isNetworkAvailable(context)) {
        try {
            HttpURLConnection urlc = (HttpURLConnection) (new URL("http://www.google.com").openConnection());
            urlc.setRequestProperty("User-Agent", "Test");
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(1500); 
            urlc.connect();
            return (urlc.getResponseCode() == 200);
        } catch (IOException e) {
        Log.e(LOG_TAG, "Error checking internet connection", e);
        }
    } else {
    Log.d(LOG_TAG, "No network available!");
    }
    return false;
}