java - Using DateTimeFormatter on january first cause an invalid year value

Question

When i'm using a DateTimeFormatter (code bellow) on a LocalDate set to January 1st 2017 i am ending with a wrong year value.

LocalDate.of(2017,1,1).toString

This will properly display 2017-01-01 while

LocalDate.of(2017,1,1).format(DateTimeFormatter.ofPattern("dd MMM YYYY"))

Is giving me: 01 janv. 2016. Do you have any idea why this is happening?

Answer 1

Your are using the "wrong" year.

 Symbol  Meaning            Presentation    Examples  
 ------  -------            ------------    -------  
 y       year-of-era        year            2004; 04  
 Y       week-based-year    year            1996; 96

Source : DateTimeFormatter

This is basicly using the first day of the current week to see in what year it was instead of the actual day.

One of the issues is that this is Local dependant...

You should have used DateTimeFormatter.ofPattern("dd MMM yyyy").