[jira] Updated: (LUCENE-1736) DateTools.java general improvements

> DateTools.java general improvements
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>
>                 Key: LUCENE-1736
>                 URL: https://issues.apache.org/jira/browse/LUCENE-1736
>             Project: Lucene - Java
>          Issue Type: Improvement
>    Affects Versions: 2.9
>            Reporter: David Smiley
>            Priority: Minor
>         Attachments: cleanerDateTools.patch
>
>
> Applying the attached patch shows the improvements to DateTools.java that I think should be done. All logic that does anything at all is moved to instance methods of the inner class Resolution. I argue this is more object-oriented.
> 1. In cases where Resolution is an argument to the method, I can simply invoke the appropriate call on the Resolution object. Formerly there was a big branch if/else.
> 2. Instead of "synchronized" being used seemingly everywhere, synchronized is used to sync on the object that is not threadsafe, be it a DateFormat or Calendar instance.
> 3. Since different DateFormat and Calendar instances are created per-Resolution, there is now less lock contention since threads using different resolutions will not use the same locks.
> 4. The old implementation of timeToString rounded the time before formatting it. That's unnecessary since the format only includes the resolution desired.
> 5. round() now uses a switch statement that benefits from fall-through (no break).
> Another debatable improvement that could be made is putting the resolution instances into an array indexed by format length. This would mean I could remove the switch in lookupResolutionByLength() and avoid the length constants there. Maybe that would be a bit too over-engineered when the switch is fine.