public static Calendar reduceCalendarMin(Calendar calendar){
  int roundedHours=Math.round(calendar.get(Calendar.MINUTE) / 60f);
  calendar.add(Calendar.HOUR,roundedHours);
  calendar.set(Calendar.MILLISECOND,0);
  calendar.set(Calendar.SECOND,0);
  calendar.set(Calendar.MINUTE,0);
  return calendar;
}

public static Calendar reduceCalendarMin ( Calendar calendar ) { int roundedHours = Math . round ( calendar . get ( Calendar . MINUTE ) / 60f ) ; calendar . add ( Calendar . HOUR , roundedHours ) ; calendar . set ( Calendar . MILLISECOND , 0 ) ; calendar . set ( Calendar . SECOND , 0 ) ; calendar . set ( Calendar . MINUTE , 0 ) ; return calendar ; }
sets the supplied calendar object with 0 values for fields lower than hour
