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Comment by pjmlp | Hacker News Reader

I am happy that Java is popular.

I know it since Sun introduced it and it was a saner experience than C++ back in the day, when each compiler implemented their own vision of the ongoing working standard.

There are only three things I don't like about Java, proper AOT compilation is only available in commercial JDKs and lack of value types, and use of @Overrides annotation instead of adding a proper keyword.

The first two will hopefully get addressed in Java 10, assuming Oracle doesn't change their minds about the language.

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So true about value types. However this will flip flop the whole memory experience in JDK9. I mean even if a LocalDateTime could be represented as a Value Type would be a significant amount of memory saving on our backend. And there is other stuff which adds a unnecessary amount, too. I mean we still get a lot of Long / Int boxes. Hopefully Java 10 will reduce that.

We are on Scala and I guess Valhalla will also make Scala even more awesome with Value Types. I could consider that half of the case classes could be real Value Types.

Another one would be having Optional finally being a value type and do away with the whole issue of Optional being null when APIs play dirty.

I agree with your points, but would like to add another one: runtime generic type erasure needs to go. Whether it is through reification or some other means, I don't care, but it feels like every single time I sit down to write some solid core-of-the-program basic code, I run up against erasure.

It's probably not every time, but you get the point.

That said, I think that Java 8 is in a good state, and I really liked its improvements. For Java 9, the new modularization system seems interesting, and I'll be happy to ditch classpaths!

> runtime generic type erasure needs to go.

Is is part of the value type related changes.

http://www.oracle.com/technetwork/java/javase/community/jlss...

How it will actually look like is still WIP.

I think you should be very careful with statements like that. The Valhalla work adds a mechanism by which generic types can be reified, but reference types in Java are not proposed to be reified as that would cause big interoperability problems with existing code. However the mechanism introduced for reifying value generics could be used by other JVM languages to provide reified reference generic types.

So HashMap<MyRefClass> will always remain the same class as HashMap<Object> when created in Java code, but might not be the same in another JVM language, and HashMap<MyValueType> will never be the same class as HashMap<Object>.

True, but nothing prevents them to have an ImprovedHashMap<any MyRefClass>.

I couldn't agree more with you. Erasure was one of the top boneheaded decisions made in the history of Java development. The irony was that it was done in the name of backwards compatibility that, in practice, was unnecessary. The runtime and API changes introduced Java5 we so large that byte-compatibility was no useful during the transition.

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