How to set default date in DateField?

if((activitiesFilterControl != null) && (activitiesFilterControl.getDateFrom() == null) && (activitiesFilterControl.getDateTo() == null))
{
    Date now = new Date();
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(now);
    calendar.add(Calendar.MONTH, -1);

    activitiesFilterControl.setDateTo(now); // now
    activitiesFilterControl.setDateFrom(calendar.getTime()); // one month before now
}