ADF 11G : How to Calculate the Difference Between Two Date ?

    oracle.jbo.domain.Date

    private Number differenceBetweenTwoDate( Date startDate, Date endDate)
    {
       if (startDate == null)
           startDate = new Date(Date.getCurrentDate()); // assume today

       if (endDate == null)
            endDate = new Date(Date.getCurrentDate());  // asume today again

       Timestamp tsStart = startDate.timestampValue();
       Timestamp tsEnd = endDate.timestampValue();

       long ndays = (tsEnd.getTime() - tsStart.getTime()) / MILI_SECONDS_PER_DAY;

       return new Number(ndays);
    }