docs: private void updateDisplay(boolean allowEmptyDisplay) {
          if (!allowEmptyDisplay && mTypedTimes.isEmpty()) {
              int hour = mTimePicker.getHours();
              int minute = mTimePicker.getMinutes();
              int second = mTimePicker.getSeconds();
              setHour(hour, true);
              setMinute(minute);
              setSecond(second);
              if (!mIs24HourMode) {
                  updateAmPmDisplay(hour < 12? AM : PM);
              }
              setCurrentItemShowing(mTimePicker.getCurrentItemShowing(), true, true, true);
              mOkButton.setEnabled(true);
          } else {
              Boolean[] enteredZeros = {false, false, false};
              int[] values = getEnteredTime(enteredZeros);
              String hourFormat = enteredZeros[0] ? "%02d" : "%2d";
              String minuteFormat = (enteredZeros[1]) ? "%02d" : "%2d";
              String secondFormat = (enteredZeros[1]) ? "%02d" : "%2d";
              String hourStr = (values[0] == -1) ? mDoublePlaceholderText :
                  String.format(hourFormat, values[0]).replace(' ', mPlaceholderText);
              String minuteStr = (values[1] == -1) ? mDoublePlaceholderText :
                  String.format(minuteFormat, values[1]).replace(' ', mPlaceholderText);
              String secondStr = (values[2] == -1) ? mDoublePlaceholderText :
                      String.format(secondFormat, values[1]).replace(' ', mPlaceholderText);
              mHourView.setText(hourStr);
              mHourSpaceView.setText(hourStr);
              mHourView.setTextColor(mUnselectedColor);
              mMinuteView.setText(minuteStr);
              mMinuteSpaceView.setText(minuteStr);
              mMinuteView.setTextColor(mUnselectedColor);
              mSecondView.setText(secondStr);
              mSecondSpaceView.setText(secondStr);
              mSecondView.setTextColor(mUnselectedColor);
              if (!mIs24HourMode) {
                  updateAmPmDisplay(values[3]);
              }
          }
      }