CountDownTimer使用

CountDownTimer(總共倒數幾毫秒，間隔幾毫秒)

override兩個方法，onTick()代表每經過一個interval所剩餘的毫秒數，onFinish()代表完成倒數後做什麼處理

CountDownTimer countDownTimer = new CountDownTimer(30000, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                activityMainBinding.tvCount.setText((millisUntilFinished / 1000) + "");
            }

            @Override
            public void onFinish() {
                activityMainBinding.tvCount.setText("DONE!");
            }
        }.start();