Problem with parsing of cron expression in Java with specific listed words

Question

Problem with parsing of cron expression in Java with specific listed words

274 Views Asked by Nikita.Itransition At 19 July 2021 at 12:56

I have a cron expression with symbols words and digits:

0/5 14,18,3-39,52 * ? JAN,MAR,SEP MON-FRI 2002-2010

And I have a regexp for parsing of this cron expression for Java:

^([\d,\-\*\/]*\s+){3}([(LW)\d,\-\*\?\/]+\s+)([(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC)\d\,\-\*\?\/\#]+\s+)([(SUN|MON|TUE|WED|THU|FRI|SAT)\(LW)\d,\-\*\?\/\#]+\s*)([\d,\-\*\/\#]+){0,1}$

It works almost fine, but there is a problem. If I add an additional letter for any of words (for example: 'JAAAN') it also parses this cron expression. I need help. How can I solve it to parse only specific word in all my combination (as listed), such as 'JAN' or 'FEB' but not 'JANU' or 'FEBR'.

Please, I need help!

Original Q&A

There are 1 best solutions below

**Ryszard Czech** · Answer 1 · 2021-07-24T21:06:04.293000

You did not provide enough data, so it won't be pretty:

^([\d,*\/-]*\s+){3}(\(LW\)|[\d,*?\/-]+)\s+((?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC|[\d,*?\/#-]+)(?:\s*,\s*(?:JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC|[\d,*?\/#-]+))*)\s*((?:SUN|MON|TUE|WED|THU|FRI|SAT|\(LW\)|[\d*?\/#-]+)(?:\s*(?:SUN|MON|TUE|WED|THU|FRI|SAT|\(LW\)|[\d*?\/#-]+))*)([\d,*\/#-]*)$

See regex proof.

EXPLANATION

--------------------------------------------------------------------------------
  ^                        the beginning of the string
--------------------------------------------------------------------------------
  (                        group and capture to \1 (3 times):
--------------------------------------------------------------------------------
    [\d,*\/-]*               any character of: digits (0-9), ',',
                             '*', '\/', '-' (0 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
    \s+                      whitespace (\n, \r, \t, \f, and " ") (1
                             or more times (matching the most amount
                             possible))
--------------------------------------------------------------------------------
  ){3}                     end of \1 (NOTE: because you are using a
                           quantifier on this capture, only the LAST
                           repetition of the captured pattern will be
                           stored in \1)
--------------------------------------------------------------------------------
  (                        group and capture to \2:
--------------------------------------------------------------------------------
    \(                       '('
--------------------------------------------------------------------------------
    LW                       'LW'
--------------------------------------------------------------------------------
    \)                       ')'
--------------------------------------------------------------------------------
   |                        OR
--------------------------------------------------------------------------------
    [\d,*?\/-]+              any character of: digits (0-9), ',',
                             '*', '?', '\/', '-' (1 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
  )                        end of \2
--------------------------------------------------------------------------------
  \s+                      whitespace (\n, \r, \t, \f, and " ") (1 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  (                        group and capture to \3:
--------------------------------------------------------------------------------
    (?:                      group, but do not capture:
--------------------------------------------------------------------------------
      JAN                      'JAN'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      FEB                      'FEB'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      MAR                      'MAR'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      APR                      'APR'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      MAY                      'MAY'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      JUN                      'JUN'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      JUL                      'JUL'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      AUG                      'AUG'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      SEP                      'SEP'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      OCT                      'OCT'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      NOV                      'NOV'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      DEC                      'DEC'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      [\d,*?\/#-]+             any character of: digits (0-9), ',',
                               '*', '?', '\/', '#', '-' (1 or more
                               times (matching the most amount
                               possible))
--------------------------------------------------------------------------------
    )                        end of grouping
--------------------------------------------------------------------------------
    (?:                      group, but do not capture (0 or more
                             times (matching the most amount
                             possible)):
--------------------------------------------------------------------------------
      \s*                      whitespace (\n, \r, \t, \f, and " ")
                               (0 or more times (matching the most
                               amount possible))
--------------------------------------------------------------------------------
      ,                        ','
--------------------------------------------------------------------------------
      \s*                      whitespace (\n, \r, \t, \f, and " ")
                               (0 or more times (matching the most
                               amount possible))
--------------------------------------------------------------------------------
      (?:                      group, but do not capture:
--------------------------------------------------------------------------------
        JAN                      'JAN'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        FEB                      'FEB'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        MAR                      'MAR'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        APR                      'APR'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        MAY                      'MAY'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        JUN                      'JUN'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        JUL                      'JUL'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        AUG                      'AUG'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        SEP                      'SEP'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        OCT                      'OCT'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        NOV                      'NOV'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        DEC                      'DEC'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        [\d,*?\/#-]+             any character of: digits (0-9), ',',
                                 '*', '?', '\/', '#', '-' (1 or more
                                 times (matching the most amount
                                 possible))
--------------------------------------------------------------------------------
      )                        end of grouping
--------------------------------------------------------------------------------
    )*                       end of grouping
--------------------------------------------------------------------------------
  )                        end of \3
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  (                        group and capture to \4:
--------------------------------------------------------------------------------
    (?:                      group, but do not capture:
--------------------------------------------------------------------------------
      SUN                      'SUN'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      MON                      'MON'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      TUE                      'TUE'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      WED                      'WED'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      THU                      'THU'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      FRI                      'FRI'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      SAT                      'SAT'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      \(                       '('
--------------------------------------------------------------------------------
      LW                       'LW'
--------------------------------------------------------------------------------
      \)                       ')'
--------------------------------------------------------------------------------
     |                        OR
--------------------------------------------------------------------------------
      [\d*?\/#-]+              any character of: digits (0-9), '*',
                               '?', '\/', '#', '-' (1 or more times
                               (matching the most amount possible))
--------------------------------------------------------------------------------
    )                        end of grouping
--------------------------------------------------------------------------------
    (?:                      group, but do not capture (0 or more
                             times (matching the most amount
                             possible)):
--------------------------------------------------------------------------------
      \s*                      whitespace (\n, \r, \t, \f, and " ")
                               (0 or more times (matching the most
                               amount possible))
--------------------------------------------------------------------------------
      (?:                      group, but do not capture:
--------------------------------------------------------------------------------
        SUN                      'SUN'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        MON                      'MON'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        TUE                      'TUE'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        WED                      'WED'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        THU                      'THU'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        FRI                      'FRI'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        SAT                      'SAT'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        \(                       '('
--------------------------------------------------------------------------------
        LW                       'LW'
--------------------------------------------------------------------------------
        \)                       ')'
--------------------------------------------------------------------------------
       |                        OR
--------------------------------------------------------------------------------
        [\d*?\/#-]+              any character of: digits (0-9), '*',
                                 '?', '\/', '#', '-' (1 or more times
                                 (matching the most amount possible))
--------------------------------------------------------------------------------
      )                        end of grouping
--------------------------------------------------------------------------------
    )*                       end of grouping
--------------------------------------------------------------------------------
  )                        end of \4
--------------------------------------------------------------------------------
  (                        group and capture to \5:
--------------------------------------------------------------------------------
    [\d,*\/#-]*              any character of: digits (0-9), ',',
                             '*', '\/', '#', '-' (0 or more times
                             (matching the most amount possible))
--------------------------------------------------------------------------------
  )                        end of \5
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string

Problem with parsing of cron expression in Java with specific listed words

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