It’s no secret that while Java possess probably the most widely distributed, cross-platform, and common user interface libraries, graphical Java applications on the whole simply stand out for the wrong reasons. Whether the GUI comes in the form of the Abstract Window Toolkit (AWT) or Swing, each can be far from pretty and often do not mesh well with the platform they are being run on. For instance, running an AWT or Swing application can be an almost alien experience, no matter what operating system you are using, because neither uses the native control widgets. Even AWT, being a ‘thin’ layer above the native controls, often looks completely bizarre. On Windows Vista AWT looks more like Windows 3.1 than anything else. Thankfully there is a nice alternative in the IBM created (and now Eclipse maintained) SWT.
The Standard Widget Toolkit, or SWT, passes all GUI rendering responsibilities onto the host operating system. This allows for some interesting advantages like hardware rendered drawing for free (as an example). It also provides for a native look and feel because its actually using the real native widgets. So when run on Windows it looks like a regular Windows application and when run on Linux it looks like a Linux (GTK+) application. It also works on the Mac as well as a few other obscure platforms.
Unfortunately because the application is now creating widgets outside of the JVM you are suddenly responsible for freeing the memory. There is no automatic garbage collection in the world of SWT. It’s not all bad however as freeing a parent object, like a window (referred to as a shell in SWT lingo), automatically frees all of its related child objects as well. Simply call the .dispose() method and 9 times out of 10 you are done.
Another other caveat is that you will still need to package the correct swt.jar file for your target platform. For instance Windows has its own version of swt.jar, as does Linux, and Mac, and so on and so forth. While this is rather annoying it does offer some interesting trade-offs. For instance you do not need to recompile your code just because you want to run it on a different platform; simply swap out the swt.jar file and watch as the exact same code generates completely different native GUIs. I even wrote a simple program that first checks what platform it is being run on and then downloads the correct swt.jar file before launching the GUI. This makes releasing the exact same package very simple.
So how do you start using SWT? Head over to http://www.eclipse.org/swt/ and download the newest stable version for your platform of choice. Depending on how you will be programing, all you have to then do is add the enclosed swt.jar to your class path. If you’re using Eclipse, or a similar IDE, you can simply add the source as either part of you project, or as a separate referenced one, and take full advantage of the auto-complete as well. Perhaps I’ll get around to posting a more thorough how-to guide at some point in the future.
Like most things in software SWT is not perfect. There are still other challenges to overcome, such as creating each individual platforms’ unique user experience to compliment their native GUI toolkits. That said if you’re looking for a way to leverage the widespread nature of Java, while still creating an application that looks like it belongs, SWT might just be what you’re looking for.