Simple BroadcastReceiver won"t work

I try to develope a simple Broadcastreceiver.

Android BroadCastReceiver refresh all activities

I have an issue using BroadCastreceiver to refresh activities in my application. I'm using a service which is doing some calculations and in onDestroy() method I'm doing this :

Android - Get preference from activity to broadcast receiver

I'm developing an Android app but I have a problem. When I try to get a saved preference from my Activity and use it in a BroadcastReceiver , it tells me that string I'm looking for doesn't exist.

ON & OFF Android Broadcastreceiver

Im creating an app in which i do a task when i receive a call (detect RINGING state with a BROADCASTRECEIVER ).My question is that,can I register and unregister (literally;ON and OFF) his broadcastreceiver from an activity having 2 buttons;say one for ON and another for OFF?

BroadcastReceiver not working on Android 3.0

I have a plugin framework which uses broadcast intents for communication between main application and plugins. On start main app sends a broadcast intent