JDK dateformatter parsing DayOfWeek in German locale, java8 vs java9

Question

I have tried some code in Java 8 (1.8.0_77) and Java 9 (Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode))

DateTimeFormatter dtf = DateTimeFormatte         


        

Answer 1

The abbreviatiions "Mo", "Di" etc. without dot have not disappeared in CLDR but are accessible via standalone-mode. You should change your pattern using the standalone format symbol "c" instead of "e":

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("ccc", Locale.GERMAN);
DayOfWeek mo = dtf.parse("Mo", DayOfWeek::from);

Indeed, I consider the change of underlying data as breaking backwards compatibility (concrete as behavioural break).