There are some CRs reported that some localized date, or time format patterns are not correct, or some localized pattern simbols returned by simpledataformat.toLocalizedPattern are not correct.

Please refer to CR 6369299 and 4265184.

The localized data are saved in jdk/src/share/classes/sun/text/resources/FormatData_xx.java. The problem is that the localized patterns or pattern symbols have been used for long time. If we directly change the localized pattern or pattern symbol, there will be compatibility issue.

The existing programs written in Java will output localized date or time in different format which should be unexpected for users, or there will be execption thrown when existing java program use localized dateformat simbols that are not supported anymore in the new release. An exmaple is CR 4994312.

So to fix the l10n (locale data) CRs like 6369299, there needs to be some architectual change as prerequisite, so that the fix in localized dateformat data will not cause compatibility issue.