Java Question how to write implemetaions in a wrapper or libraries?

in the library , I must implement some interface with this code:
public class newActivity extends Activity implements someEventHandler{
onReq(BaseReq req){ .....}
}
how I get the callback with the same name , so I can get the message send from the server?

Don't create an activity. Create a different class that implements the interface. You can raise events with ba.raiseEvent.