code: private static void bindService() {
          synchronized (Command.class) {
              if (!IS_BIND) {
                  Context context = Cmd.getContext();
                  if (context == null) {
                      throw new NullPointerException("Context not should null. Please call Cmd.init(Context)");
                  } else {
                      // Cmd service
                      context.bindService(new Intent(context, CommandService.class), I_CONN, Context.BIND_AUTO_CREATE);
                      IS_BIND = true;
                  }
              }
          }
      }
docs: Start bind Service