8229471: Calendar under a specific timezone changes HOUR field when MILLISECOND field is changed

[naoto.sato at oracle.com]

Hi Masanori,

Thank you for looking at the issue and your contribution. I am also  
investigating it (as an assignee of the bug), and looking at this old  
issue:

https://bugs.openjdk.java.net/browse/JDK-4177484

The comment suggests that the existing behavior is the expected one. In  
fact, your fix would break some regression test cases in  
jdk/java/util/Calendar/CalendarRegression.java.

I will need some more archaeological investigation, but I am inclined to  
close it as not an issue at the moment.

Naoto

On 9/12/19 12:16 AM, Yano, Masanori wrote:
> Hello.
> 
> I think JDK-8229471 occurs because a change of TimeZone is not considered in getTime().
> To resolve this problem, isTimeSet flag must be set to false when setTimeZone() is called.
> 
> Please review the following change.
> 
> diff -r e1269de19aa5 src/java.base/share/classes/java/util/Calendar.java
> --- a/src/java.base/share/classes/java/util/Calendar.java      Thu Aug 22 14:09:36 2019 -0700
> +++ b/src/java.base/share/classes/java/util/Calendar.java      Thu Sep 12 11:45:37 2019 +0900
> @@ -2901,7 +2901,7 @@
>            * generally, a call to setTimeZone() affects calls to set() BEFORE AND
>            * AFTER it up to the next call to complete().
>            */
> -        areAllFieldsSet = areFieldsSet = false;
> +        isTimeSet = areAllFieldsSet = areFieldsSet = false;
>       }
> 
>       /**
> diff -r e1269de19aa5 test/jdk/java/util/Calendar/Bug8229471.java
> --- /dev/null  Thu Jan 01 00:00:00 1970 +0000
> +++ b/test/jdk/java/util/Calendar/Bug8229471.java      Thu Sep 12 11:45:37 2019 +0900
> @@ -0,0 +1,22 @@
> +/*
> + *@test
> + *@bug 8229471
> + *@summary test for recompute when Calendar.setTimeZone()
> + */
> +
> +import java.util.Calendar;
> +import java.util.Date;
> +import java.util.Locale;
> +import java.util.TimeZone;
> +
> +public class Bug8229471 {
> +    public static void main(String[] args) throws Exception {
> +        Calendar calendar = Calendar.getInstance(new Locale("en", "US"));
> +        Date date1 = calendar.getTime();
> +        calendar.setTimeZone(TimeZone.getTimeZone("Europe/Budapest"));
> +        Date date2 = calendar.getTime();
> +        if (date1.equals(date2)) {
> +            throw new RuntimeException("Bug8229471: failed. TimeZone is not applied.");
> +        }
> +    }
> +}
> 
> Regards,
> Masanori Yano
>