How to parse dates in multiple formats using SimpleDateFormat

Question

I am trying to parse some dates that are coming out of a document  It would appear users have entered these dates in a similar but not exact format   here are the formats   9 09 9 2009 09 2009 9 1 2009 9-1-2009    What is the best  way to go about trying to parse all of these  These seem to be the most common  but I guess what is hanging me up is that if i have a pattern of  M yyyy  wont that always catch before  MM yyyy   Do I have to set up my try catch blocks nested in a least restrictive to most restrictive way  it seems like it sure is going to take a lot of code duplication to get this right

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This solution checks all the possible formats before throwing an exception  This solution is more convenient if you are trying to test for multiple date formats   Date extractTimestampInput String strDate       final List lt String gt  dateFormats   Arrays asList  yyyy-MM-dd HH mm ss SSS    yyyy-MM-dd             for String format  dateFormats           SimpleDateFormat sdf   new SimpleDateFormat format           try              return sdf parse strDate             catch  ParseException e                   intentionally empty                         throw new IllegalArgumentException  Invalid input for date  Given    strDate     expecting format yyyy-MM-dd HH mm ss SSS or yyyy-MM-dd

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I m solved this problem more simple way using regex  fun parseTime time  String    Long       val longRegex      d 4  -  d 2  -  d 2    w  d 2    d 2    d 2    d 3  Z         val shortRegex      d 4  -  d 2  -  d 2    w  d 2    d 2    d 2 Z         val longDateFormat   SimpleDateFormat  yyyy-MM-dd T HH mm ss sssXXX       val shortDateFormat   SimpleDateFormat  yyyy-MM-dd T HH mm ssXXX        return when           Pattern matches longRegex  time  - gt  longDateFormat parse time  time         Pattern matches shortRegex  time  - gt  shortDateFormat parse time  time         else - gt  throw InvalidParamsException INVALID TIME MESSAGE  null

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You ll need to use a different SimpleDateFormat object for each different pattern  That said  you don t need that many different ones  thanks to this      Number  For formatting  the number of pattern letters is the minimum number of digits  and shorter numbers are zero-padded to this amount  For parsing  the number of pattern letters is ignored unless it s needed to separate two adjacent fields    So  you ll need these formats     M y   that covers 9 09  9 2009  and 09 2009   M d y   that covers 9 1 2009   M-d-y   that covers 9-1-2009    So  my advice would be to write a method that works something like this  untested           List lt String gt  formatStrings   Arrays asList  M y    M d y    M-d-y            Date tryParse String dateString        for  String formatString   formatStrings                try                       return new SimpleDateFormat formatString  parse dateString                     catch  ParseException e                return null

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Matt s approach above is fine  but please be aware that you will run into problems if you use it to differentiate between dates of the format y M d and d M y  For instance  a formatter initialised with y M d will accept a date like 01 01 2009 and give you back a date which is clearly not what you wanted  I fixed the issue as follows  but I have limited time and I m not happy with the solution for 2 main reasons    It violates one of Josh Bloch s quidelines  specifically  don t use exceptions to handle program flow   I can see the getDateFormat   method becoming a bit of a nightmare if you needed it to handle lots of other date formats    If I had to make something that could handle lots and lots of different date formats and needed to be highly performant  then I think I would use the approach of creating an enum which linked each different date regex to its format  Then use MyEnum values   to loop through the enum and test with if myEnum getPattern   matches date   rather than catching a dateformatexception   Anway  that being said  the following can handle dates of the formats  y M d   y-M-d   y M d   d M y   d-M-y   d M y  and all other variations of those which include time formats as well   import java text ParseException  import java text SimpleDateFormat  import java util Date   public class DateUtil       private static final String   timeFormats     HH mm ss   HH mm        private static final String   dateSeparators         -             private static final String DMY FORMAT    dd sep MM sep yyyy       private static final String YMD FORMAT    yyyy sep MM sep dd        private static final String ymd template      d 4  sep   d 2  sep   d 2          private static final String dmy template      d 2  sep   d 2  sep   d 4           public static Date stringToDate String input       Date date   null      String dateFormat   getDateFormat input       if dateFormat    null           throw new IllegalArgumentException  Date is not in an accepted format     input              for String sep   dateSeparators           String actualDateFormat   patternForSeparator dateFormat  sep             try first with the time         for String time   timeFormats           date   tryParse input actualDateFormat         time           if date    null               return date                                didn t work  try without the time formats         date   tryParse input actualDateFormat           if date    null           return date                       return date             private static String getDateFormat String date       for String sep   dateSeparators           String ymdPattern   patternForSeparator ymd template  sep           String dmyPattern   patternForSeparator dmy template  sep           if date matches ymdPattern            return YMD FORMAT                    if date matches dmyPattern            return DMY FORMAT                      return null             private static String patternForSeparator String template  String sep       return template replace   sep    sep              private static Date tryParse String input  String pattern       try          return new SimpleDateFormat pattern  parse input             catch  ParseException e         return null

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Using DateTimeFormatter it can be achieved as below    import java text SimpleDateFormat  import java time LocalDateTime  import java time ZoneOffset  import java time ZonedDateTime  import java time format DateTimeFormatter  import java time temporal TemporalAccessor  import java util Date  import java util TimeZone   public class DateTimeFormatTest        public static void main String   args             String pattern     yyyy-MM-dd   T     HH mm ss  SSSSSSSz   SSS XXX  X               String timeSample    2018-05-04T13 49 01 7047141Z           SimpleDateFormat simpleDateFormatter   new SimpleDateFormat  dd MM yy HH mm ss            DateTimeFormatter formatter   DateTimeFormatter ofPattern pattern           TemporalAccessor accessor   formatter parse timeSample           ZonedDateTime zTime   LocalDateTime from accessor  atZone ZoneOffset UTC            Date date new Date zTime toEpochSecond   1000           simpleDateFormatter setTimeZone TimeZone getTimeZone ZoneOffset UTC            System out println simpleDateFormatter format date                     Pay attention at String pattern  this is the combination of multiple patterns  In open   and close   square brackets you can mention any kind of patterns

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I was having multiple date formats into json  and was extracting csv with universal format  I looked multiple places  tried different ways  but at the end I m able to convert with the following simple code    private String getDate String anyDateFormattedString         SuppressWarnings  deprecation       Date date   new Date anyDateFormattedString       SimpleDateFormat dateFormat   new SimpleDateFormat yourDesiredDateFormat           String convertedDate   dateFormat format date       return convertedDate

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In Apache commons lang  DateUtils class we have a method called parseDate  We can use this for parsing the date   Also another library Joda-time also have the method to parse the date

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For the modern answer I am ignoring the requirement to use SimpleDateFormat  While using this class for parsing was a good idea in 2010 when this question was asked  it is now long outdated  The replacement  DateTimeFormatter  came out in 2014  The idea in the following is pretty much the same as in the accepted answer   private static DateTimeFormatter   parseFormatters   Stream of  M yy    M y    M d y    M-d-y            map DateTimeFormatter  ofPattern           toArray DateTimeFormatter    new    public static YearMonth parseYearMonth String input        for  DateTimeFormatter formatter   parseFormatters            try               return YearMonth parse input  formatter             catch  DateTimeParseException dtpe                   ignore  try next format                     throw new IllegalArgumentException  Could not parse     input       This parses each of the input strings from the question into a year-month of 2009-09  It   s important to try the two-digit year first since  M y  could also parse 9 09  but into 0009-09 instead   A limitation of the above code is it ignores the day-of-month from the strings that have one  like 9 1 2009  Maybe it   s OK as long as most formats have only month and year  To pick it up  we   d have to try LocalDate parse   rather then YearMonth parse   for the formats that include d in the pattern string  Surely it can be done

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If working in Java 1 8 you can leverage the DateTimeFormatterBuilder  public static boolean isTimeStampValid String inputString        DateTimeFormatterBuilder dateTimeFormatterBuilder   new DateTimeFormatterBuilder                append DateTimeFormatter ofPattern        yyyy-MM-dd T HH mm ss SSSZ       yyyy-MM-dd           DateTimeFormatter dateTimeFormatter   dateTimeFormatterBuilder toFormatter         try           dateTimeFormatter parse inputString           return true        catch  DateTimeParseException e            return false            See post  Java 8 Date equivalent to Joda  39 s DateTimeFormatterBuilder with multiple parser formats

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Implemented the same in scala  Please help urself with converting to Java  the core logic and functions used stays the same    import java text SimpleDateFormat import org apache commons lang time DateUtils  object MultiDataFormat     def main args  Array String      val dates  Array  2015-10-31   26 12 2015   19-10-2016    val possibleDateFormats Array String    Array  yyyy-MM-dd   dd MM yyyy   dd-MM-yyyy    val sdf    new SimpleDateFormat  yyyy-MM-dd     change it as per the requirement   for  date lt -dates        val outputDate   DateUtils parseDateStrictly date  possibleDateFormats      System out println  inputDate    gt      date      outputDate    gt     outputDate         sdf format outputDate

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Here is the complete example  with main method  which can be added as a utility class in your project  All the format mentioned in SimpleDateFormate API is supported in the below method    import java text ParseException  import java text SimpleDateFormat  import java util Date   import org apache commons lang time DateUtils   public class DateUtility        public static Date parseDate String inputDate             Date outputDate   null          String   possibleDateFormats                                        yyyy MM dd G  at  HH mm ss z                        EEE  MMM d    yy                        h mm a                        hh  o  clock  a  zzzz                        K mm a  z                        yyyyy MMMMM dd GGG hh mm aaa                        EEE  d MMM yyyy HH mm ss Z                        yyMMddHHmmssZ                        yyyy-MM-dd T HH mm ss SSSZ                        yyyy-MM-dd T HH mm ss SSSXXX                        YYYY- W ww-u                        EEE  dd MMM yyyy HH mm ss z                         EEE  dd MMM yyyy HH mm zzzz                        yyyy-MM-dd T HH mm ssZ                        yyyy-MM-dd T HH mm ss SSSzzzz                         yyyy-MM-dd T HH mm sszzzz                        yyyy-MM-dd T HH mm ss z                        yyyy-MM-dd T HH mm ssz                         yyyy-MM-dd T HH mm ss                        yyyy-MM-dd T HHmmss SSSz                        yyyy-MM-dd                        yyyyMMdd                        dd MM yy                        dd MM yyyy                            try                outputDate   DateUtils parseDate inputDate  possibleDateFormats               System out println  inputDate    gt      inputDate      outputDate    gt      outputDate              catch  ParseException e                   TODO Auto-generated catch block             e printStackTrace                       return outputDate              public static String formatDate Date date  String requiredDateFormat            SimpleDateFormat df   new SimpleDateFormat requiredDateFormat           String outputDateFormatted   df format date           return outputDateFormatted             public static void main String   args             DateUtility parseDate  20181118            DateUtility parseDate  2018-11-18            DateUtility parseDate  18 11 18            DateUtility parseDate  18 11 2018            DateUtility parseDate  2018 11 18 AD at 12 08 56 PDT            System out println              DateUtility parseDate  Wed  Nov 18   18            DateUtility parseDate  12 08 PM            DateUtility parseDate  12 o clock PM  Pacific Daylight Time            DateUtility parseDate  0 08 PM  PDT            DateUtility parseDate  02018 Nov 18 AD 12 08 PM            System out println              DateUtility parseDate  Wed  18 Nov 2018 12 08 56 -0700            DateUtility parseDate  181118120856-0700            DateUtility parseDate  2018-11-18T12 08 56 235-0700            DateUtility parseDate  2018-11-18T12 08 56 235-07 00            DateUtility parseDate  2018-W27-3

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What about just defining multiple patterns  They might come from a config file containing known patterns  hard coded it reads like   List lt SimpleDateFormat gt  knownPatterns   new ArrayList lt SimpleDateFormat gt     knownPatterns add new SimpleDateFormat  yyyy-MM-dd T HH mm ss Z      knownPatterns add new SimpleDateFormat  yyyy-MM-dd T HH mm ss Z      knownPatterns add new SimpleDateFormat  yyyy-MM-dd T HH mm ss     knownPatterns add new SimpleDateFormat  yyyy-MM-dd   HH mm ss     knownPatterns add new SimpleDateFormat  yyyy-MM-dd T HH mm ssXXX      for  SimpleDateFormat pattern   knownPatterns        try              Take a try         return new Date pattern parse candidate  getTime            catch  ParseException pe               Loop on         System err println  No known Date format found      candidate   return null

[java] How to parse dates in multiple formats using SimpleDateFormat

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