Regex date format validation on Java

Question

I m just wondering if there is a way  maybe with regex  to validate that an input on a Java desktop app is exactly an string formated as   YYYY-MM-DD    I ve searched but with no success   Thank you

User · Answer

The following regex will accept YYYY-MM-DD (within the range 1600-2999 year) formatted dates taking into consideration leap years:

 ^((?:(?:1[6-9]|2[0-9])\d{2})(-)(?:(?:(?:0[13578]|1[02])(-)31)|((0[1,3-9]|1[0-2])(-)(29|30))))$|^(?:(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))(-)02(-)29)$|^(?:(?:1[6-9]|2[0-9])\d{2})(-)(?:(?:0[1-9])|(?:1[0-2]))(-)(?:0[1-9]|1\d|2[0-8])$

Examples:

You can test it here.

Note: if you want to accept one digit as month or day you can use:

 ^((?:(?:1[6-9]|2[0-9])\d{2})(-)(?:(?:(?:0?[13578]|1[02])(-)31)|((0?[1,3-9]|1[0-2])(-)(29|30))))$|^(?:(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))(-)0?2(-)29)$|^(?:(?:1[6-9]|2[0-9])\d{2})(-)(?:(?:0?[1-9])|(?:1[0-2]))(-)(?:0?[1-9]|1\d|2[0-8])$

I have created the above regex starting from this solution

User · Answer

Putting it all together      REGEX doesn t validate values  like  2010-19-19     SimpleDateFormat does not check format   2010-1-2    1-0002-003  are accepted      it s necessary to use both to validate format and value     public static boolean isValid String text        if  text    null     text matches    d 4 - 01   d- 0-3   d            return false      SimpleDateFormat df   new SimpleDateFormat  yyyy-MM-dd        df setLenient false       try           df parse text           return true        catch  ParseException ex            return false               A ThreadLocal can be used to avoid the creation of a new SimpleDateFormat for each call  It is needed in a multithread context since the SimpleDateFormat is not thread safe   private static final ThreadLocal lt SimpleDateFormat gt  format   new ThreadLocal lt SimpleDateFormat gt           Override     protected SimpleDateFormat initialValue             SimpleDateFormat df   new SimpleDateFormat  yyyy-MM-dd            df setLenient false           System out println  created            return df            public static boolean isValid String text        if  text    null     text matches    d 4 - 01   d- 0-3   d            return false      try           format get   parse text           return true        catch  ParseException ex            return false             same can be done for a Matcher  that also is not thread safe

User · Answer

I would go with a simple regex which will check that days doesn t have more than 31 days and months no more than 12  Something like      0  1-9   12  0-9  3 01  - 0  1-9  1 012  -  18 19 20 21   d  d    This is the format  dd-MM-yyyy   You can tweak it to your needs  for example take off the   to make the leading 0 required - now its optional   and then use a custom logic to cut down to the specific rules like leap years February number of days case  and other months number of days cases  See the DateChecker code below     I am choosing this approach since I tested that this is the best one when performance is taken into account  I checked this  1st  approach versus 2nd approach of validating a date against a regex that takes care of the other use cases  and 3rd approach of using the same simple regex above in combination with SimpleDateFormat parse date   The 1st approach was 4 times faster than the 2nd approach  and 8 times faster than the 3rd approach  See the self contained date checker and performance tester main class at the bottom  One thing that I left unchecked is the joda time approach s    The more efficient date time library    Date checker code   class DateChecker        private Matcher matcher      private Pattern pattern       public DateChecker String regex            pattern   Pattern compile regex                         Checks if the date format is a valid         Uses the regex pattern to match the date first          Than additionally checks are performed on the boundaries of the days taken the month into account  leap years are covered                   param date the date that needs to be checked          return if the date is of an valid format or not              public boolean check final String date            matcher   pattern matcher date           if  matcher matches                  matcher reset                if  matcher find                      int day   Integer parseInt matcher group 1                    int month   Integer parseInt matcher group 2                    int year   Integer parseInt matcher group 3                     switch  month                    case 1                  case 3                  case 5                  case 7                  case 8                  case 10                  case 12  return day  lt  32                  case 4                  case 6                  case 9                  case 11  return day  lt  31                  case 2                       int modulo100   year   100                        http   science howstuffworks com science-vs-myth everyday-myths question50 htm                     if   modulo100    0  amp  amp  year   400    0      modulo100    0  amp  amp  year   LEAP STEP    0                               its a leap year                         return day  lt  30                        else                           return day  lt  29                                        default                      break                                                    return false             public String getRegex             return pattern pattern              Date checking testing and performance testing     import java text ParseException  import java text SimpleDateFormat  import java util ArrayList  import java util List  import java util regex Matcher  import java util regex Pattern   public class Tester        private static final String   validDateStrings   new String             1-1-2000     leading 0s for day and month optional          01-1-2000     leading 0 for month only optional          1-01-2000     leading 0 for day only optional          01-01-1800     first accepted date          31-12-2199     last accepted date          31-01-2000     January has 31 days          31-03-2000     March has 31 days          31-05-2000     May has 31 days          31-07-2000     July has 31 days          31-08-2000     August has 31 days          31-10-2000     October has 31 days          31-12-2000     December has 31 days          30-04-2000     April has 30 days          30-06-2000     June has 30 days          30-09-2000     September has 30 days          30-11-2000     November has 30 days            private static final String   invalidDateStrings   new String             00-01-2000     there is no 0-th day          01-00-2000     there is no 0-th month          31-12-1799     out of lower boundary date          01-01-2200     out of high boundary date          32-01-2000     January doesn t have 32 days          32-03-2000     March doesn t have 32 days          32-05-2000     May doesn t have 32 days          32-07-2000     July doesn t have 32 days          32-08-2000     August doesn t have 32 days          32-10-2000     October doesn t have 32 days          32-12-2000     December doesn t have 32 days          31-04-2000     April doesn t have 31 days          31-06-2000     June doesn t have 31 days          31-09-2000     September doesn t have 31 days          31-11-2000     November doesn t have 31 days          001-02-2000     SimpleDateFormat valid date  day with leading 0s  even with lenient set to false          1-0002-2000     SimpleDateFormat valid date  month with leading 0s  even with lenient set to false          01-02-0003     SimpleDateFormat valid date  year with leading 0s  even with lenient set to false          01 01-2000       invalid separator between day and month          01-01 2000       invalid separator between month and year          01 01-2000       invalid separator between day and month          01-01 2000       invalid separator between month and year          01 01-2000       invalid separator between day and month          01-01 2000       invalid separator between month and year          01-01-2000-12345     only whole string should be matched          01-13-2000     month bigger than 13                        These constants will be used to generate the valid and invalid boundary dates for the leap years   For no leap year  Feb  28 valid and Feb  29 invalid  for a leap year Feb  29 valid and Feb  30 invalid                 private static final int LEAP STEP   4      private static final int YEAR START   1800      private static final int YEAR END   2199                  This date regex will find matches for valid dates between 1800 and 2199 in the format of  dd-MM-yyyy          The leading 0 is optional              private static final String DATE REGEX      0  1-9   12  0-9  3 01  - 0  13578  1 02  - 18 19 20 21  0-9  2     0  1-9   12  0-9  30 - 0  469  11 - 18 19 20 21  0-9  2     0  1-9  1 0-9  2 0-8  - 0 2 - 18 19 20 21  0-9  2    29- 0 2 -   18 19 20 21  04 08  2468  048   13579  26    2000                     This date regex is similar to the first one  but with the difference of matching only the whole string  So  01-01-2000-12345  won t pass with a match         Keep in mind that String matches tries to match only the whole string              private static final String DATE REGEX ONLY WHOLE STRING         DATE REGEX                        The simple regex  without checking for 31 day months and leap years               private static final String DATE REGEX SIMPLE     0  1-9   12  0-9  3 01  - 0  1-9  1 012  -  18 19 20 21   d  d                    This date regex is similar to the first one  but with the difference of matching only the whole string  So  01-01-2000-12345  won t pass with a match              private static final String DATE REGEX SIMPLE ONLY WHOLE STRING         DATE REGEX SIMPLE             private static final SimpleDateFormat SDF   new SimpleDateFormat  dd-MM-yyyy        static           SDF setLenient false              private static final DateChecker dateValidatorSimple   new DateChecker DATE REGEX SIMPLE       private static final DateChecker dateValidatorSimpleOnlyWholeString   new DateChecker DATE REGEX SIMPLE ONLY WHOLE STRING                    param args             public static void main String   args            DateTimeStatistics dateTimeStatistics   new DateTimeStatistics            boolean shouldMatch   true          for  int i   0  i  lt  validDateStrings length  i                  String validDate   validDateStrings i               matchAssertAndPopulateTimes                      dateTimeStatistics                      shouldMatch  validDate                      shouldMatch   false          for  int i   0  i  lt  invalidDateStrings length  i                  String invalidDate   invalidDateStrings i                matchAssertAndPopulateTimes dateTimeStatistics                      shouldMatch  invalidDate                      for  int year   YEAR START  year  lt   YEAR END   1   year                  FebruaryBoundaryDates februaryBoundaryDates   createValidAndInvalidFebruaryBoundaryDateStringsFromYear year               shouldMatch   true              matchAssertAndPopulateTimes dateTimeStatistics                      shouldMatch  februaryBoundaryDates getValidFebruaryBoundaryDateString                 shouldMatch   false              matchAssertAndPopulateTimes dateTimeStatistics                      shouldMatch  februaryBoundaryDates getInvalidFebruaryBoundaryDateString                        dateTimeStatistics calculateAvarageTimesAndPrint               private static void matchAssertAndPopulateTimes              DateTimeStatistics dateTimeStatistics              boolean shouldMatch  String date            dateTimeStatistics addDate date           matchAndPopulateTimeToMatch date  DATE REGEX  shouldMatch  dateTimeStatistics getTimesTakenWithDateRegex             matchAndPopulateTimeToMatch date  DATE REGEX ONLY WHOLE STRING  shouldMatch  dateTimeStatistics getTimesTakenWithDateRegexOnlyWholeString             boolean matchesSimpleDateFormat   matchWithSimpleDateFormatAndPopulateTimeToMatchAndReturnMatches date  dateTimeStatistics getTimesTakenWithSimpleDateFormatParse             matchAndPopulateTimeToMatchAndReturnMatchesAndCheck                  dateTimeStatistics getTimesTakenWithDateRegexSimple    shouldMatch                  date  matchesSimpleDateFormat  DATE REGEX SIMPLE           matchAndPopulateTimeToMatchAndReturnMatchesAndCheck                  dateTimeStatistics getTimesTakenWithDateRegexSimpleOnlyWholeString    shouldMatch                  date  matchesSimpleDateFormat  DATE REGEX SIMPLE ONLY WHOLE STRING            matchAndPopulateTimeToMatch date  dateValidatorSimple  shouldMatch  dateTimeStatistics getTimesTakenWithdateValidatorSimple             matchAndPopulateTimeToMatch date  dateValidatorSimpleOnlyWholeString  shouldMatch  dateTimeStatistics getTimesTakenWithdateValidatorSimpleOnlyWholeString                private static void matchAndPopulateTimeToMatchAndReturnMatchesAndCheck              List lt Long gt  times              boolean shouldMatch  String date  boolean matchesSimpleDateFormat  String regex            boolean matchesFromRegex   matchAndPopulateTimeToMatchAndReturnMatches date  regex  times           assert    matchesSimpleDateFormat  amp  amp  matchesFromRegex    shouldMatch     Parsing with SimpleDateFormat and date     date     nregex     regex     nshouldMatch     shouldMatch             private static void matchAndPopulateTimeToMatch String date  String regex  boolean shouldMatch  List lt Long gt  times            boolean matches   matchAndPopulateTimeToMatchAndReturnMatches date  regex  times           assert   matches   shouldMatch     date     date     nregex     regex     nshouldMatch     shouldMatch             private static void matchAndPopulateTimeToMatch String date  DateChecker dateValidator  boolean shouldMatch  List lt Long gt  times            long timestampStart          long timestampEnd          boolean matches          timestampStart   System nanoTime            matches   dateValidator check date           timestampEnd   System nanoTime            times add timestampEnd - timestampStart           assert   matches   shouldMatch     date     date     ndateValidator with regex     dateValidator getRegex       nshouldMatch     shouldMatch             private static boolean matchAndPopulateTimeToMatchAndReturnMatches String date  String regex  List lt Long gt  times            long timestampStart          long timestampEnd          boolean matches          timestampStart   System nanoTime            matches   date matches regex           timestampEnd   System nanoTime            times add timestampEnd - timestampStart           return matches             private static boolean matchWithSimpleDateFormatAndPopulateTimeToMatchAndReturnMatches String date  List lt Long gt  times            long timestampStart          long timestampEnd          boolean matches   true          timestampStart   System nanoTime            try               SDF parse date             catch  ParseException e                matches   false            finally               timestampEnd   System nanoTime                times add timestampEnd - timestampStart                     return matches             private static FebruaryBoundaryDates createValidAndInvalidFebruaryBoundaryDateStringsFromYear int year            FebruaryBoundaryDates februaryBoundaryDates          int modulo100   year   100            http   science howstuffworks com science-vs-myth everyday-myths question50 htm         if   modulo100    0  amp  amp  year   400    0      modulo100    0  amp  amp  year   LEAP STEP    0                 februaryBoundaryDates   new FebruaryBoundaryDates                      createFebruaryDateFromDayAndYear 29  year                        createFebruaryDateFromDayAndYear 30  year                                   else               februaryBoundaryDates   new FebruaryBoundaryDates                      createFebruaryDateFromDayAndYear 28  year                        createFebruaryDateFromDayAndYear 29  year                                           return februaryBoundaryDates             private static String createFebruaryDateFromDayAndYear int day  int year            return String format   d-02- d   day  year              static class FebruaryBoundaryDates           private String validFebruaryBoundaryDateString          String invalidFebruaryBoundaryDateString          public FebruaryBoundaryDates String validFebruaryBoundaryDateString                  String invalidFebruaryBoundaryDateString                super                this validFebruaryBoundaryDateString   validFebruaryBoundaryDateString              this invalidFebruaryBoundaryDateString   invalidFebruaryBoundaryDateString                    public String getValidFebruaryBoundaryDateString                 return validFebruaryBoundaryDateString                    public void setValidFebruaryBoundaryDateString                  String validFebruaryBoundaryDateString                this validFebruaryBoundaryDateString   validFebruaryBoundaryDateString                    public String getInvalidFebruaryBoundaryDateString                 return invalidFebruaryBoundaryDateString                    public void setInvalidFebruaryBoundaryDateString                  String invalidFebruaryBoundaryDateString                this invalidFebruaryBoundaryDateString   invalidFebruaryBoundaryDateString                       static class DateTimeStatistics           private List lt String gt  dates   new ArrayList lt String gt             private List lt Long gt  timesTakenWithDateRegex   new ArrayList lt Long gt             private List lt Long gt  timesTakenWithDateRegexOnlyWholeString   new ArrayList lt Long gt             private List lt Long gt  timesTakenWithDateRegexSimple   new ArrayList lt Long gt             private List lt Long gt  timesTakenWithDateRegexSimpleOnlyWholeString   new ArrayList lt Long gt             private List lt Long gt  timesTakenWithSimpleDateFormatParse   new ArrayList lt Long gt             private List lt Long gt  timesTakenWithdateValidatorSimple   new ArrayList lt Long gt             private List lt Long gt  timesTakenWithdateValidatorSimpleOnlyWholeString   new ArrayList lt Long gt             public List lt String gt  getDates                 return dates                    public List lt Long gt  getTimesTakenWithDateRegex                 return timesTakenWithDateRegex                    public List lt Long gt  getTimesTakenWithDateRegexOnlyWholeString                 return timesTakenWithDateRegexOnlyWholeString                    public List lt Long gt  getTimesTakenWithDateRegexSimple                 return timesTakenWithDateRegexSimple                    public List lt Long gt  getTimesTakenWithDateRegexSimpleOnlyWholeString                 return timesTakenWithDateRegexSimpleOnlyWholeString                    public List lt Long gt  getTimesTakenWithSimpleDateFormatParse                 return timesTakenWithSimpleDateFormatParse                    public List lt Long gt  getTimesTakenWithdateValidatorSimple                 return timesTakenWithdateValidatorSimple                    public List lt Long gt  getTimesTakenWithdateValidatorSimpleOnlyWholeString                 return timesTakenWithdateValidatorSimpleOnlyWholeString                    public void addDate String date                dates add date                     public void addTimesTakenWithDateRegex long time                timesTakenWithDateRegex add time                     public void addTimesTakenWithDateRegexOnlyWholeString long time                timesTakenWithDateRegexOnlyWholeString add time                     public void addTimesTakenWithDateRegexSimple long time                timesTakenWithDateRegexSimple add time                     public void addTimesTakenWithDateRegexSimpleOnlyWholeString long time                timesTakenWithDateRegexSimpleOnlyWholeString add time                     public void addTimesTakenWithSimpleDateFormatParse long time                timesTakenWithSimpleDateFormatParse add time                     public void addTimesTakenWithdateValidatorSimple long time                timesTakenWithdateValidatorSimple add time                     public void addTimesTakenWithdateValidatorSimpleOnlyWholeString long time                timesTakenWithdateValidatorSimpleOnlyWholeString add time                      private void calculateAvarageTimesAndPrint                 long   sumOfTimes   new long 7               int timesSize   timesTakenWithDateRegex size                for  int i   0  i  lt  timesSize  i                      sumOfTimes 0     timesTakenWithDateRegex get i                   sumOfTimes 1     timesTakenWithDateRegexOnlyWholeString get i                   sumOfTimes 2     timesTakenWithDateRegexSimple get i                   sumOfTimes 3     timesTakenWithDateRegexSimpleOnlyWholeString get i                   sumOfTimes 4     timesTakenWithSimpleDateFormatParse get i                   sumOfTimes 5     timesTakenWithdateValidatorSimple get i                   sumOfTimes 6     timesTakenWithdateValidatorSimpleOnlyWholeString get i                             System out println  AVG from timesTakenWithDateRegex  in nanoseconds       double  sumOfTimes 0    timesSize               System out println  AVG from timesTakenWithDateRegexOnlyWholeString  in nanoseconds       double  sumOfTimes 1    timesSize               System out println  AVG from timesTakenWithDateRegexSimple  in nanoseconds       double  sumOfTimes 2    timesSize               System out println  AVG from timesTakenWithDateRegexSimpleOnlyWholeString  in nanoseconds       double  sumOfTimes 3    timesSize               System out println  AVG from timesTakenWithSimpleDateFormatParse  in nanoseconds       double  sumOfTimes 4    timesSize               System out println  AVG from timesTakenWithDateRegexSimple   timesTakenWithSimpleDateFormatParse  in nanoseconds       double   sumOfTimes 2    sumOfTimes 4     timesSize               System out println  AVG from timesTakenWithDateRegexSimpleOnlyWholeString   timesTakenWithSimpleDateFormatParse  in nanoseconds       double   sumOfTimes 3    sumOfTimes 4     timesSize               System out println  AVG from timesTakenWithdateValidatorSimple  in nanoseconds       double  sumOfTimes 5    timesSize               System out println  AVG from timesTakenWithdateValidatorSimpleOnlyWholeString  in nanoseconds       double  sumOfTimes 6    timesSize                        static class DateChecker            private Matcher matcher          private Pattern pattern           public DateChecker String regex                pattern   Pattern compile regex                                     Checks if the date format is a valid             Uses the regex pattern to match the date first              Than additionally checks are performed on the boundaries of the days taken the month into account  leap years are covered                           param date the date that needs to be checked              return if the date is of an valid format or not                      public boolean check final String date                matcher   pattern matcher date               if  matcher matches                      matcher reset                    if  matcher find                          int day   Integer parseInt matcher group 1                        int month   Integer parseInt matcher group 2                        int year   Integer parseInt matcher group 3                         switch  month                        case 1                      case 3                      case 5                      case 7                      case 8                      case 10                      case 12  return day  lt  32                      case 4                      case 6                      case 9                      case 11  return day  lt  31                      case 2                           int modulo100   year   100                            http   science howstuffworks com science-vs-myth everyday-myths question50 htm                         if   modulo100    0  amp  amp  year   400    0      modulo100    0  amp  amp  year   LEAP STEP    0                                   its a leap year                             return day  lt  30                            else                               return day  lt  29                                                default                          break                                                                    return false                     public String getRegex                 return pattern pattern                        Some useful notes  - to enable the assertions  assert checks  you need to use -ea argument when running the tester   In eclipse this is done by editing the Run Debug configuration -  Arguments tab -  VM Arguments -  insert  -ea  - the regex above is bounded to years 1800 to 2199 - you don t need to use   at the beginning and   at the end to match only the whole date string  The String matches takes care of that  - make sure u check the valid and invalid cases and change them according the rules that you have  - the  only whole string  version of each regex gives the same speed as the  normal  version  the one without   and     If you see performance differences this is because java  gets used  to processing the same instructions so the time lowers  If you switch the lines where the  normal  and the  only whole string  version execute  you will see this proven     Hope this helps someone  Cheers  Despot

User · Answer

Use the following regular expression     d 4 - d 2 - d 2     as in  if  str matches    d 4 -  d 2 -  d 2                   With the matches method  the anchors   and    beginning and end of string  respectively  are present implicitly

User · Answer

Construct a SimpleDateFormat with the mask  and then call  SimpleDateFormat parse String s  ParsePosition p

User · Answer

java time  The proper  and easy  way to do date time validation using Java 8  is to use the java time format DateTimeFormatter class  Using a regex for validation isn t really ideal for dates  For the example case in this question   DateTimeFormatter formatter   DateTimeFormatter ofPattern  yyyy-MM-dd     try       LocalDate date   formatter parse text  LocalDate  from     catch  DateTimeParseException e           Thrown if text could not be parsed in the specified format     This code will parse the text  validate that it is a valid date  and also return the date as a LocalDate object  Note that the DateTimeFormatter class has a number of static predefined date formats matching ISO standards if your use case matches any of them

User · Answer

For fine control  consider an InputVerifier using the SimpleDateFormat  YYYY-MM-dd   suggested by Steve B

User · Answer

You need more than a regex  for example  9999-99-00  isn t a valid date  There s a SimpleDateFormat class that s built to do this  More heavyweight  but more comprehensive   e g    SimpleDateFormat format   new SimpleDateFormat  yyyy-MM-dd     boolean isValidDate string input         try             format parse input             return true              catch ParseException e             return false             Unfortunately  SimpleDateFormat is both heavyweight and not thread-safe

User · Answer

If you want a simple regex then it won t be accurate  https   www freeformatter com java-regex-tester html ad-output offers a tool to test your Java regex  Also  at the bottom you can find some suggested regexes for validating a date   ISO date format  yyyy-mm-dd      0-9  4 -   0 13578   10 12  - 0 1-9   1-2  0-9  3 0-1     02- 0 1-9   1-2  0-9      0 469  11 - 0 1-9   1-2  0-9  30       ISO date format  yyyy-mm-dd  with separators  -  or     or     or      Forces usage of same separator accross date     0-9  4   -        0 13578   10 12   1 0 1-9   1-2  0-9  3 0-1     02 1 0 1-9   1-2  0-9      0 469  11  1 0 1-9   1-2  0-9  30       United States date format  mm dd yyyy       0 13578   10 12    0 1-9   1-2  0-9  3 0-1     02  0 1-9   1-2  0-9      0 469  11   0 1-9   1-2  0-9  30     0-9  4     Hours and minutes  24 hours format  HH MM      20 21 22 23  01  d  d     0-5  d  1 2      Good luck

User · Answer

This will do it regex      19 20   d  d - 0  1-9  1 012  - 0  1-9   12  0-9  3 01     This will take care of valid formats and valid dates   It will not validate the correct days of the month i e  leap year   String regex       19 20   d  d - 0  1-9  1 012  - 0  1-9   12  0-9  3 01       Assert assertTrue  Date  matched    Pattern matches regex   2011-1-1     Assert assertFalse  Date  month   not matched    Pattern matches regex   2011-13-1       Good luck

User · Answer

Below added code is working for me if you are using pattern   dd-MM-yyyy    public boolean isValidDate String date            boolean check          String date1      0  1-9   12  0-9  3 01  - 0  1-9  1 012  -  12  0-9  3              check   date matches date1            return check

[java] Regex date format validation on Java

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