question: public static DateFormat toDateTimeFormat ( String dateTimeFormat , TimeZone tz , Locale locale ) { DateFormat df = null ; if ( UtilValidate . isEmpty ( dateTimeFormat ) ) { df = DateFormat . getDateTimeInstance ( DateFormat . SHORT , DateFormat . MEDIUM , locale ) ; } else { df = new SimpleDateFormat ( dateTimeFormat , locale == null ? Locale . getDefault ( ) : locale ) ; } df . setTimeZone ( tz ) ; return df ; }
target:  Returns an initialized DateFormat object.