RFR: 8267587: Update java.util to use enhanced switch [v6]

[Tagir F.Valeev]

On Wed, 26 May 2021 02:22:42 GMT, Tagir F. Valeev <tvaleev at openjdk.org> wrote:

>> Inspired by PR#4088. Most of the changes are done automatically using IntelliJ IDEA refactoring. Some manual adjustments are also performed, including indentations, moving comments, extracting common cast out of switch expression branches, etc.
>> 
>> I also noticed that there are some switches having one branch only in JapaneseImperialCalendar.java. Probably it would be better to replace them with `if` statement?
>
> Tagir F. Valeev has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - JapaneseImperialCalendar: use switch expressions
>  - Use yield in java.util.Calendar.Builder.build

src/java.base/share/classes/java/util/JapaneseImperialCalendar.java line 1316:

> 1314:         JapaneseImperialCalendar jc = getNormalizedCalendar();
> 1315:         LocalGregorianCalendar.Date date = jc.jdate;
> 1316:         int normalizedYear = date.getNormalizedYear();

This variable was unused

src/java.base/share/classes/java/util/JapaneseImperialCalendar.java line 1423:

> 1421:             case WEEK_OF_MONTH -> {
> 1422:                 LocalGregorianCalendar.Date jd = jcal.getCalendarDate(Long.MAX_VALUE, getZone());
> 1423:                 if (date.getEra() == jd.getEra() && date.getYear() == jd.getYear()) {

I inverted the `if` condition here, as it was negated and a much shorter branch was in `else`.

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PR: https://git.openjdk.java.net/jdk/pull/4161