Android - BroadcastReceiver when wifi or 3g network state changed

You need to set a permissions on android manifest

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

Set up your receiver

<receiver android:name=".NetworkChangeReceiver" >

            <intent-filter>

                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />

            </intent-filter>

</receiver>

Receiver code

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.net.ConnectivityManager;

import android.net.NetworkInfo;

import android.util.Log;

public class NetworkChangeReceiver extends BroadcastReceiver {

    @Override

    public void onReceive(Context context, Intent intent) {

    ConnectivityManager connMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo wifi = connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

        NetworkInfo mobile = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);

        boolean isConnected = wifi != null && wifi.isConnectedOrConnecting() || mobile != null && mobile.isConnectedOrConnecting(); 

        if (isConnected) {

            Log.d("Network Available ", "YES");

        }else{

           Log.d("Network Available ", "NO");

        }

    }

}