Java Regex用于标识所有日期

我试图识别格式

日-月-年、日-月、月-年和年的所有可能的日期表达式

我的正则表达式：

[0-9]{0,2}（[Jj]anuary |[Ff]ebruary |[Mm]arch |[Aa]pril |[Mm]ay |[Jj]une |[Jj]uly |[Aa]ugust |[Ss]eptember |[Oo]ctober |[Nn]overmber |[Dd]ecember）{0,1]4}
缺少表达式
DAY-MONTH

如何修复它？
请尝试下一步：

(?i)(?<=\s|^)((\d{1,2} )?(january|february|march|april|may|june|july|august|september|october|november|december)( \d{4})?)|\d{4}(?=\s|$)

（？i）（？
NODE                     EXPLANATION
----------------------------------------------------------------------------
  (?i)                     set flags for this block (case-
                           insensitive) (with ^ and $ matching
                           normally) (with . not matching \n)
                           (matching whitespace and # normally)
----------------------------------------------------------------------------
  (?<=                     look behind to see if there is:
----------------------------------------------------------------------------
    \s                       whitespace (\n, \r, \t, \f, and " ")
----------------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------------
    ^                        the beginning of the string
----------------------------------------------------------------------------
  )                        end of look-behind
----------------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------------
    (                        group and capture to \2 (optional
                             (matching the most amount possible)):
----------------------------------------------------------------------------
      \d{1,2}                  digits (0-9) (between 1 and 2 times
                               (matching the most amount possible))
----------------------------------------------------------------------------
                               ' '
----------------------------------------------------------------------------
    )?                       end of \2 (NOTE: because you are using a
                             quantifier on this capture, only the
                             LAST repetition of the captured pattern
                             will be stored in \2)
----------------------------------------------------------------------------
    (                        group and capture to \3:
----------------------------------------------------------------------------
      january                  'january'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      february                 'february'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      march                    'march'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      april                    'april'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      may                      'may'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      june                     'june'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      july                     'july'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      august                   'august'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      september                'september'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      october                  'october'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      november                 'november'
----------------------------------------------------------------------------
     |                        OR
----------------------------------------------------------------------------
      december                 'december'
----------------------------------------------------------------------------
    )                        end of \3
----------------------------------------------------------------------------
    (                        group and capture to \4 (optional
                             (matching the most amount possible)):
----------------------------------------------------------------------------
                               ' '
----------------------------------------------------------------------------
      \d{4}                    digits (0-9) (4 times)
----------------------------------------------------------------------------
    )?                       end of \4 (NOTE: because you are using a
                             quantifier on this capture, only the
                             LAST repetition of the captured pattern
                             will be stored in \4)
----------------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------------
 |                        OR
----------------------------------------------------------------------------
  \d{4}                    digits (0-9) (4 times)
----------------------------------------------------------------------------
  (?=                      look ahead to see if there is:
----------------------------------------------------------------------------
    \s                       whitespace (\n, \r, \t, \f, and " ")
----------------------------------------------------------------------------
   |                        OR
----------------------------------------------------------------------------
    $                        before an optional \n, and the end of
                             the string
----------------------------------------------------------------------------
  )                        end of look-ahead