public static DateTime toDateSimple(String str,TimeZone timeZone) throws PageException {
  DateTime dt=toDateSimple(str,CONVERTING_TYPE_OFFSET,true,timeZone,null);
  if (dt == null)   throw new ExpressionException("can't cast [" + str + "] to date value");
  return dt;
}

public static DateTime toDateSimple ( String str , TimeZone timeZone ) throws PageException { DateTime dt = toDateSimple ( str , CONVERTING_TYPE_OFFSET , true , timeZone , null ) ; if ( dt == null ) throw new ExpressionException ( "can't cast [" + str + "] to date value" ) ; return dt ; }
converts a object to a datetime object , returns null if invalid string
