May 2015 - core-libs-dev

RFR: JDK-8074003 java.time.zone.ZoneRules.getOffset(java.time.Instant) can be optimized
by Peter Levart 04 May '15

04 May '15

Hi again, Here's another optimization to be reviewed that has been discussed a while ago (just rebased from webrev.01) and approved by Stephen: http://cr.openjdk.java.net/~plevart/jdk9-dev/ZoneOffsetTransition.epochSeco… The discussion about it is intermingled with the ZoneId.systemDefault() discussion and starts about here: http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-February/031873.h… The rationale for the optimization is speeding-up the conversion from epoch time to LocalDateTime. This conversion uses ZoneRules.getOffset(Instant) where there is a loop over ZoneOffsetTransition[] array that searches for 1st transition that has its toEpochSecond value less than the Instant's epochSecond. This calls ZoneOffsetTransition.toEpochSecond repeatedly, converting ZoneOffsetTransition.transition which is a LocalDateTime to epochSecond. This repeated conversion is unnecessary, as ZoneOffsetTransition[] array is part of ZoneRules which is cached. Optimizing the ZoneOffsetTransition implementation (keeping both LocalDateTime variant and eposhSecond variant of transition time as the object's state) speeds up this conversion. Regards, Peter

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Additional method on Stream
by Stephen Colebourne 02 May '15

02 May '15

This is a request for an additional method on java.util.stream.Stream. Having written quite a bit of code in Java 8 now, one annoyance keeps on coming up, filtering and casting the stream. Currently, it is necessary to do this: return input.stream() .filter(Foo.class::isInstance) .map(Foo.class::cast) .someTerminalOperation(); or return input.stream() .filter(t -> t instanceof Foo) .map(t -> (Foo) t) .someTerminalOperation(); Really, what is needed is this: return input.stream() .filter(Foo.class) .someTerminalOperation(); For info, Guava's FluentIterable has such a method. The new method signature would be something like: public Stream<R> filter(Class<R> cls); As far as I can see, there is no problem in implementing this in both serial and parallel modes, as it is essentially just a convenience. Thoughts? Stephen

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Unicode command-line parameters on Windows
by Anthony Vanelverdinghe 01 May '15

01 May '15

Hi I would like to use a Java program for Windows file associations. However, this doesn't work when the file to be opened contains non-ASCII Unicode characters in its path. There are several related issues about Windows Unicode support (e.g. JDK-4488646, JDK-4519026, JDK-4900150, JDK-6475368, JDK-6937897, JDK-8029584), some of which are resolved with "Future Project" and the last one having Fix Version 10 [1]. A while ago there was also a draft JEP about this with ID 8047097 [2]. However, the JEP is no longer available & the associated JDK issue is private. In January a code submission was proposed by Microsoft developers [3], but it's unclear from the thread what happened with the submission. From these observations, I'd guess there will be a "Windows Unicode support" project targeted for Java SE 10? Who can shed some light on the current plans for this? Will there be improvements in this area in Java SE 9? Thanks in advance, Anthony [1] https://bugs.openjdk.java.net/browse/JDK-8029584 [2] http://openjdk.java.net/jeps/8047097 [3] http://mail.openjdk.java.net/pipermail/core-libs-dev/2015-January/031068.ht…

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