What differences will Java 7 have from Java 6, and what will it mean to us Java programmers?
I'm very curious about what the future of java holds, and I've been able to find some info on Java 7, but I want to know what all that info really means. Like what will a modular JDK do for programs?
The preeminent source for information on the state of Java 7 is Alex Miller's blog.
To answer your question: there are no earth-shattering changes (unlike, say, Java 5), just minor improvements. All the big changes like closures, extension methods, reified generics and first-class properties are out.
The official website is here:
and a full list of features can be found here:
I think the contents of the release are still subject to change. I'm not quite sure what it really means from a developer perspective - the most obvious change ( as you mention) is that of modularisation (JSR277/Jigsaw). It's still a bit of a contentious issue, there's some official discussion here from the lead developer's (Mark Reinhold) blog:
The interesting thing here is that Apache Harmony (which is developed out of the JCP) is already a modular JDK via OSGi manifests, more info on this here:
Hope that helps, it'll be an interesting release!
As far as what changes you'll see in your day-to-day work, my guess is that the major impact will be stuff like JSR 203 which overhauls the file system API. If JSR 310 is included, then it would also have a major impact on how you interact with any aspect of the date and time APIs. Many of the other JSRs will only impact you if you happen to already do something in that particular area (JMX - JSR 255, concurrency - JSR 166, etc).
I think it's unknown at this point how much JSR 294 and Jigsaw will impact us day to day. It's possible that it will be a new and important way to define modules that will impact the way we bundle libraries, define dependencies, and deploy our apps. Or it may just be used in the JDK and ignored elsewhere. Only time will tell.
There will be a handful of language changes that come out of Project Coin but they are mostly going to be small useful but not revolutionary changes that help remove some boilerplate.
I think the biggest thing most people will notice may be performance. As usual, each JDK brings a whole new set of performance optimizations. We've already seen some very encouraging results in String performance, array performance, and a new concurrent garbage collector (G1). I suspect many people will find that their existing code will work and run noticeably faster than it did in the past.
JSR292 is the big one for me -- dynamic language support. Everything else pales into comparison next to that. I expect to see a massive improvement in JRuby, Jython, and Groovy out of that.
I'm surprised that they dropped closures -- wonder why? No way to handle the scoping without incredible amounts of pain?
I think JSR 308 and the @Nullable/@Nonnull annotations will affect people. I expect to turn on @Nonnull as the default setting and then spend 1/2 a week making my codebase comply. I'm probably not the only team lead planning this.
You can prepare now by downloading the prototype from the JSR 308 website (http://groups.csail.mit.edu/pag/jsr308/) and running the checker against your codebase today.