作Sm快遞櫃的每一個fragment的倒計時

當我返回的到上個頁面的時候 發現 時間沒有從新計時。

@Override
public void onCreate(@Nullable Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    FragmentManager fm = getFragmentManager();
    System.out.println("" + fm);
    fm.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener()
    {
        @Override
        public void onBackStackChanged()
        {
            if (BaseFragment.this.isVisible()) {
                startTimer();
            } else {
                stopTimer();
            }
        }
    });
}

protected int startTimer()
    {
        recLen = 60;
        callbackTime(recLen);
        mhandler.removeMessages(RUNNER_MSG_CODE);
        Message msg = Message.obtain();
        msg.what = RUNNER_MSG_CODE;
        msg.obj = runnable;
        mhandler.sendMessageDelayed(msg, 1000);
        // Log.e("startTimer","startTimer");
        return recLen;
    }

    private void stopTimer()
    {
        mhandler.removeMessages(RUNNER_MSG_CODE);
        recLen = -1;
        // Log.e("stopTimer","stopTimer");

    }


    public void reStartTimer()
    {
        //  Log.e("reStartTimer","reStartTimer");
        recLen = 60;

    }

    private Handler mhandler =
            new Handler(Looper.getMainLooper())
            {
                @Override
                public void handleMessage(Message msg)
                {
                    if (msg.what == RUNNER_MSG_CODE) {
                        this.post((Runnable) msg.obj);
                    }
                }
            };
    Runnable runnable = new Runnable()
    {
        @Override
        public void run()
        {
            recLen--;
//            cd_time.setText(recLen+"");
            callbackTime(recLen);
            // Log.e("cd_time",recLen+"=");
            if (recLen == 0) {
                mhandler.removeMessages(RUNNER_MSG_CODE);
              // backOnce();
                start(MainFragment.newInstance());
                // Log.e("BaseFragment","BaseFragment=="+recLen);
            } else if (recLen > 0) {
                Message msg = Message.obtain();
                msg.what = RUNNER_MSG_CODE;
                msg.obj = runnable;
                mhandler.sendMessageDelayed(msg, 1000);
                //  Log.e("BaseFragment","BaseFragment=="+recLen);
            } else if (recLen < 0) {
                mhandler.removeMessages(RUNNER_MSG_CODE);
                //  Log.e("BaseFragment","BaseFragment=="+recLen);
            }

        }
    };