public static DateTime toDateSimple(String str,short convertingType,boolean alsoMonthString,TimeZone timeZone) throws PageException {
  DateTime dt=toDateSimple(str,convertingType,alsoMonthString,timeZone,null);
  if (dt == null)   throw new ExpressionException("can't cast value to a Date Object");
  return dt;
}

public static DateTime toDateSimple ( String str , short convertingType , boolean alsoMonthString , TimeZone timeZone ) throws PageException { DateTime dt = toDateSimple ( str , convertingType , alsoMonthString , timeZone , null ) ; if ( dt == null ) throw new ExpressionException ( "can't cast value to a Date Object" ) ; return dt ; }
converts a object to a datetime object , returns null if invalid string
