如何在sharedpreferences中保存计时器，然后在activity重启时再次提取我必须设置一个5分钟的计时器，它应该继续从它停止的地方，当activity结束时

new CountDownTimer(300000,1000){

            @Override
            public void onTick(long millisUntilFinished) {
                timer.setText("Time Left: "+String.format("%d : %d min(s)",
                        TimeUnit.MILLISECONDS.toMinutes( millisUntilFinished),
                        TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished) -
                                TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millisUntilFinished))));
            }

            @Override
            public void onFinish() {
                timer.setVisibility(View.GONE);
            }
        }.start();

sharedpreferences类中的变量是什么？

public static final long OrderTimeLeft = 300000;