Illegal pattern character 'Y' on Ubuntu

问题:

I use this pattern SimpleDateFormat format = new SimpleDateFormat("YYYY-MM-dd HH:mm:ss"); in windows and it works, but when try on Ubuntu 10.04 it show an exception play.exceptions.JavaExecutionException: Illegal pattern character 'Y'.

I search for solution for this and found the year pattern must be change to lower-case: SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); and it works.

Can anyone can tell me the reason behind this why in Windows works but in Ubuntu didn't work if I use 'Y' instead of 'y'?

Note:

1. Play-1.2.3
2. JRE:
   1. Windows: java version "1.7.0_03" Java(TM) SE Runtime Environment (build 1.7.0_03-b05) Java HotSpot(TM) Client VM (build 22.1-b02, mixed mode, sharing)
   2. Ubuntu: java version "1.6.0_31" Java(TM) SE Runtime Environment (build 1.6.0_31-b04) Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)
3. Windows 7
4. Ubuntu 10.04

Update 24/05/2012

After I check again in my system, there is 3 JRE and my windows using JRE1.7 for default. But for Play I set running using JRE1.6.

回答1:

I search for SimpleDateFormat and got the doc from oracle.

Works in my windows because I set the default JRE to 1.7 but still running using JRE1.6 for the Play Framework.

Works on Windows because of this, JRE1.7 has added 'Y' pattern for Week year and in JRE1.6 there is no pattern for this.

回答2:

Y is not an valid pattern. y is.

As per the docs:

Letter   Date or Time Component     Presentation    Examples
G        Era designator             Text            AD
y        Year                       Year            1996; 96
M        Month in year              Month           July; Jul; 07
w        Week in year               Number          27
...

I don't know why Y would work in windows, but it is not documented. y is the correct one. And the safest.