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Comment by krg | Hacker News Reader

I'm not sure what you mean exactly, but as mentioned in the article they've built a new JavaScript engine (to replace Rhino) to be included in Java8: http://openjdk.java.net/jeps/174

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Just that an entire revolution is happening in the browser itself, I'd really like to be able to code Java directly with something GWT. I read recently that GWT has support for the latest html5 stuff, but complaints about compile time and lack of performance after compilation turn me off...

You should give GWT a go. Compile time is a valid complaint, though it can be mitigated by only producing a single permutation (browser specific output) while in development, rather than the default five-six. Also note that during development you usually don't compile but run in "dev mode", a browser plugin that runs against your actual Java code.

Performance after compilation is certainly not a problem, on the contrary the GWT output is very tight, especially with full obfuscation (aggressive optimizations, inlining etc.).

(I've written a complete HTML5 game engine in GWT: http://www.webworks.dk/enginetest)

Another valid complaint is that dev mode runs quite slow, particularly if you're developing something like a game. I read an article about how they are addressing this so that dev mode runs almost as fast as the compiled result, but can't find the link now. Maybe it's already live? Been half a year since I've used GWT.

But I second the recommendation overall. One thing I learned the hard way though, is that their widget library is pretty constraining, and a very leaky abstraction. I would consistently run up against walls using a particular widget, bang my head against it for a day or two, then scrap everything and roll my own solution. Eventually, I just used GWT to compile the core business logic of my app (which would have been a nightmare to do in JS), and did UI with the standard HTML/CSS/JS flow. Doing UI in Java is too clunky for me no matter what library I'm using though, so YMMV.

> Doing UI in Java is too clunky for me no matter what library I'm using though, so YMMV.

For sure. C#, Java, C++ are all clunky. Maybe it's the nature of the ecosystem.

This is one thing I hate about GWT: it offers tons of upside (sprites, bundles, i18n, unit-test in JUnit IF using MVP) but the downside is in the area of big-consideration of pain point.

With GWT it is possible to pretty much build your UI in HTML and simply inject key components, with event handlers etc., into the DOM structure. You would use an HTMLPanel and add(Widget widget, String id). Few people seem to be aware of this.

I used this approach to build TeamPostgreSQL (demo at http://teampostgresql.herokuapp.com/), where the designer built the entire interface in HTML and I just inject GWT widgets in the right places.

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