With over 150 bug fixes, Java 5 language support, new compiler optimizations, default visual themes, an entirely new DOM API and JavaScript overlay types, the release candidate of Google Web Toolkit 1.5 has gotten very positive feedback from early adopters, reports Google's Kelly Norton.

Writing on the Google Web Toolkit blog, Norton reported at the end of May that there are some fresh new links on the Google Code download page leading to a release candidate of Google Web Toolkit 1.5.

Then came the meat of the post, namely his summary of the features and feedback:

"Since the previous release of GWT, we've seen a lot of really great applications that demonstrate what is possible when you are able to focus on the user and stop worrying so much about browser quirks and other Ajax obstacles. Inspired by what we have seen so far, we have continued to concentrate our efforts on enabling developers to use their existing tools to create web apps that users enjoy. GWT 1.5 takes this commitment even further with exciting new features and over 150 bug fixes. And, like all GWT releases, most of the benefits are just an upgrade-and-recompile away.

We've gotten very positive feedback from early adopters and here is what they are most excited about:

Java 5 language support
It feels good to finally close out our most requested feature. GWT developers can now freely use the modern Java syntax including generics, enumerated types, annotations, auto-boxing, and so on.

New compiler optimizations increase performance
With this release of GWT, we're happy to announce that our compiler produces faster code than you would write by hand! How's that? A bunch of new compiler optimizations allow us to efficiently inline method calls, even through many layers of indirection. Translation: all the nice abstractions and clean design work that are essential to maintaining a large code base melt away in the compiler's output, giving your users the fastest possible experience. By contrast, if you were writing JavaScript by hand, you'd have to choose between writing good code and writing fast code — and when your application got to a certain size, maintainability would make the second choice impossible. With GWT 1.5, you don't have to compromise; just write good code and let the compiler make it fast.

JavaScript Overlay Types
This further enhances GWT's interoperability with the underlying JavaScript layer. “Overlay type” is a new term we're using to describe the ability to model JavaScript objects as strongly-typed Java instances with no additional runtime cost. Overlay types make it easy to provide fine-grained interop with handwritten JavaScript libraries as well as providing an optimal way to make JSON structures directly accessible to GWT code.

High-performance DOM API
Up until GWT 1.5, we've concentrated mostly on Widget-level APIs, and until the advent of overlay types (above), direct DOM programming wasn't particularly convenient. GWT 1.5 goes beyond "convenient" and well into "elegant" with an entirely new DOM API that enables type-safe, low-level DOM programming that will be both comfortable to DOM experts and free of any runtime overhead.

Default visual themes
Several default visual themes are now available by default so that developers get an attractive UI out of the box and have a good starting point to create their own custom styles in CSS."

Norton reminds interested developers that to find out more they should download the release candidate "and join us in our mission to radically improve the web experience for users."

• Google Web Toolkit: Finally Java Has Been Put into JavaScript!