Question

I’m wondering if there’s a way to somehow register as an observer for network access (and have some callback function run when the internet is avaliable), or if polling is the only way. Thanks!

Answer 1

You can register receiver:

//Callback  
private final BroadcastReceiver mNetworkStateReceiver = new BroadcastReceiver() {
    @Override
        public void onReceive(Context context, Intent intent) {
           //network state changes, you can process it, inforamtion in intent
        }
    };

//registering recievr in actibity or in service
IntentFilter mNetworkStateFilter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
registerReceiver(mNetworkStateReceiver , mNetworkStateFilter);

Detail at:
http://developer.android.com/reference/android/net/ConnectivityManager.html