JDK-8042126 : DateTimeFormatter "MMMMM" returns English value in Japanese locale
  • Type: Bug
  • Component: core-libs
  • Sub-Component: java.time
  • Affected Version: 8u5
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • Submitted: 2014-04-29
  • Updated: 2015-06-04
  • Resolved: 2014-09-26
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8u40Fixed 9 b34Fixed
DateTimeFormatter.ofPattern("MMMMM") returns English month name in Japanese 

"M" represents month-of-year, and "MMMMM" represents the narrow form.
In Japanese locale, it should return "4" for April, but it returns "A".
"A" is English abbreviated month name and not used in Japanese locale.

"LLLLL" (stand-alone month-of-year) returns "4" expectedly.

The root cause - MonthNarrows is not defined for Japanese in resource bundle.