Using broadcastreceiver only on certain activity

Question

I have two activities on is Register() and the other is ReadNews(). I am using broadcast receiver to detect internet connection automatically to execute some code.

 public void onReceive(Context context, Intent intent) {

    ConnectivityManager cm = (ConnectivityManager)context.getSystemService(
    Context.CONNECTIVITY_SERVICE);
    NetworkInfo wifiNetwork = cm.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
    if (wifiNetwork != null && wifiNetwork.isConnected()) {
        if(MyApplication.isActivityVisible() == true) {
            Log.d("WifiReceiver", "Have Wifi Connection");
            Toast.makeText(context, "تم الإتصال بالشبكة", Toast.LENGTH_LONG).show();
            if (context instanceof RegisterActivity){
                Intent i = new Intent(context,
                        ReadNews.class);
                i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(i);
            }
            else {

            }
        }
    }

How can I start the ReadNews() activity only when the internet connection goes on while the user still using the RegisterActivity() only?
I tried to use the context like if (context instanceof RegisterActivity) but that doesn't seem right.

Answer 1

Thanks to @Squonk comment, I have followed that short comment instructions to accomplish what I want to do and now I want to share summary of my code to show how this thing works:
Broadcast receiver inner class

 private BroadcastReceiver wifiReceiver =
        new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {

    //do what ever you want here
};

registering Broadcast receiver in onResume()

@Override
protected void onResume() {
    super.onResume();
    IntentFilter filter = new IntentFilter();
    filter.addAction("android.net.conn.CONNECTIVITY_CHANGE"); //or any intent filter you want 
    registerReceiver(wifiReceiver, filter);
}

unregistering Broadcast receiver in onPause

 @Override
protected void onPause() {
    super.onPause();        
    unregisterReceiver(wifiReceiver);
}

Important

Don't use an <intent-filter> in the manifest. registering the broadcast receiver must be dynamic (onResume,onPause)