android studio定时器

 private CountDownTimer afterRunTimer=new CountDownTimer(2000,2000) {
        @Override
        public void onTick(long l) {


            LogUtil.d("TAG", "onTick: afterRunTimer");
        }

        @Override
        public void onFinish() {


            afterRunTimer.cancel();

            getActivity().runOnUiThread(new Runnable() {
                @Override
                public void run() {

                    LogUtil.d("TAG", "onFinish: afterRunTimer  readSN");
                    readSN();



                }
            });


        }
    };