code: public void show() {
          if (mListener == null) {
              throw new NullPointerException(
                      "Attempting to bind null listener to SlideDateTimePicker");
          }
  
          if (mInitialDate == null) {
              setInitialDate(new Date());
          }
  
          DateTimeDialogFragment dialogFragment =
                  DateTimeDialogFragment.newInstance(
                          mListener,
                          mInitialDate,
                          mMinDate,
                          mMaxDate,
                          mIsClientSpecified24HourTime,
                          mIs24HourTime,
                          mTheme,
                          mIndicatorColor);
  
          dialogFragment.show(mFragmentManager,
                  DateTimeDialogFragment.TAG_SLIDE_DATE_TIME_DIALOG_FRAGMENT);
      }
docs: Shows the dialog to the user. Make sure to call
  {@link #setListener()} before calling this.