Since Eclipse's first release in 2001, it has become a popular environment for Java development. In the period between March 10 and May 11, 2005, users downloaded over 17,000 copies of one of the production SDK releases and over 3,500 copies of one of the stable (milestone) SDK builds on average every day. A vibrant eco-system of developers, plug-in providers, authors, and bloggers has grown up around it. Eclipse has also gained the backing of the key Java vendors including BEA, Borland, IBM, SAP, and Sybase. Developers like Eclipse because it provides a great platform for building Java applications, and companies like it because it unifies their software tools under one open source umbrella.

 In late June of this year, the latest release of the Eclipse Platform, version 3.1, will be available for download from eclipse.org. In this article, I'll highlight some of the more interesting new features it contains. I'll also discuss some of the other Eclipse projects that are re-leasing new versions at about the same time.

A New Hope for Developers
One of the major new features of Eclipse 3.1 is full support for the new language constructions in J2SE 5.0 (also called J2SE 1.5 in the old numbering scheme). Generics, annotations, enums, auto boxing, enhanced for loop, etc., - it's all in there, both in the underlying compiler and the user interface and code assistance that Eclipse is known for.

Bill Dudney, editor of Eclipse Developer's Journal with Mike Milinkovich during their live SYS-CON.TV interview.

While Eclipse didn't invent the idea of refactoring, it provides one of the most complete implementations. Eclipse 3.1 comes with a number of new and enhanced refactorings, code assistance, and "quick fixes", many in conjunction with its J2SE5 support. For example, you can put your cursor on a conventional for loop that iterates over an array (see Figure 1), press Ctrl+1, and Eclipse will offer to convert it to one of the new style for loops (see Figure 2).

At the heart of Eclipse's Java support is a fully compliant incremental Java compiler, written in Java and supporting Java language levels 1.3, 1.4, and now 5.0. Having its own compiler brings Eclipse some benefits including fast compilation, smoother debugging and refactoring, and a lot of diagnostic warnings. The compiler has found several uses outside of Eclipse. It's bundled with many popular Linux distributions and commercial applications, and recent versions of Apache Tomcat use it to compile JSPs. It forms the basis of the AspectJ compiler. And I wouldn't be surprised to see the Eclipse compiler used in the recently announced Apache Harmony project as well.

Other usability enhancements make 3.1 more productive. For example, the new release contains a more integrated help system that changes to show help for what you're doing at all times. One of the largest improvements is in the area of Preferences. Addressing a key user request, the Preference dialog now offers the ability to filter by keywords, for example, you can easily find all options having to do with "tabs" by typing that keyword into the filter box. In addition, Web-like navigation has been added to link to related preferences and go forward and backward in the history.

To make preferences easier to find, in Eclipse 3.1 the Preferences dialog can be opened directly from many editors and views through the context menu. For example, if you right-click in the Java editor and select Preferences..., the dialog will appear. Only the options related to Java editing, including those for the text editor that the Java editor inherits, are shown.

Eclipse 3.1 improves its Ant support by including the latest version of Ant, and an Ant script debugger (see Figure 3), plus many editor enhancements. Another welcome addition: the ability to import a project from an Ant build file, and to export and generate a build file from an existing Eclipse project - you can synchronize your CLASSPATH and build.xml with a few clicks. The generated build.xml is simple and clean, with a provision for a build-user.xml that you can override and still keep the benefits of build.xml generation. This is another example of the community in action: the import/export feature is based on the contribution of Richard Höfter, author of the eclipse2ant plugin.

One thing to note is that all these new features don't come with a performance penalty. Eclipse 3.1 is a lot faster and uses far less memory for common operations than version 3.0. Don't believe me? Check out the performance tests results on the download page for any recent build. These improvements are not just for Windows; Mac and Linux users will notice even it even more due to the special attention paid to those platforms. The graphs don't tell the whole story, however. In normal day-to-day work I've found Eclipse 3.1 to be much snappier than any previous version.

With developers working with ever larger and more complex projects, their IDE needs to keep up. In order to experience and study problems with large workspaces, the Platform team created one consisting of 135 separate projects and 70,000 classes and other resources. Then, using various profiling tools they identified and corrected many bottlenecks, mainly in the area of memory usage and I/O. As a result, Eclipse 3.1 can handle bigger problems in less time than before. Launching the test workspace used to take close to two minutes, but in Eclipse 3.1 it now takes under 10 seconds.

Return of the Java Client
Java started out on the desktop, and now after a brief vacation on the server side, it's returning to the desktop with a vengeance. The Rich Client Platform (RCP) is helping to spark this renaissance. RCP is a subset of Eclipse that provides a framework for application development. It includes a widget toolkit (SWT), the plug-in loaders, the help system, and other components that you can use in your own programs.

By taking advantage of this free "client middleware," you can focus on your core competencies and reduce your time-to-market. Eclipse's corporate-friendly license (EPL) allows you to reuse the code in your own programs, whether or not they are open source. You can modify and redistribute the code, as long as you return any improvements to the community.

The biggest change for RCP in Eclipse 3.1 is a set of wizards and editors for creating, building, branding, and deploying RCP applications. To create an RCP application just create a plug-in project, click the checkbox that says "Create an RCP application", select a template, and then click Finish. With a few more clicks you can export the project to create a deployable application. No more trying to figure out plug-in dependencies, tweaking configuration files, and copying plug-ins by hand. All that's handled for you in the new release.

Branded applications are supported through the new Product Configuration editor. You can change the window titles, icons, splash screens, and other branded elements of your program quickly and easily. And with the RCP Delta Pack you can create deployable packages for all supported platforms at the same time (see Figure 4).

RCP applications can take advantage of dynamic plug-ins, that is, plug-ins that come and go at runtime. This provides flexibility to the RCP application delivery model. A large application can be deployed progressively as plug-ins are loaded or on demand when extra functionality is needed. This technology was originally designed for mobile phone provisioning as part of the OSGi Service Platform, and later implemented in Eclipse by the Equinox project team. Eclipse is an active participant in OSGi, and Eclipse 3.1 includes several features slated for version 4 of the OSGi standard.

In one proof-of-concept example shown at EclipseCon, the developers demonstrated a calculator program that started out with only a plus and minus button. Using Eclipse's update manager and dynamic plug-ins, the calculator then downloaded a new plug-in that added a multiply button. All this is done in the running JVM process without a restart.