The next version of S60 that will appear in devices set to launch in 2008 will include embedded Standard Widget Toolkit support. What exactly is eSWT and why should you care as a Java developer or as an end user? It makes creating a graphical user interface practically a cakewalk. More information about eSWT on IBM’s page which happens to be down, but google cache to the rescue:
The embedded Standard Widget Toolkit (eSWT) is a subset of the well-known Java™ graphics tool kit, the Standard Widget Toolkit (SWT). It provides a set of controls, panels, and other widgets commonly used as building blocks of user interfaces (UIs). In addition to what was originally included in SWT, eSWT introduced a new component: mobile extensions (a jointly designed specification among IBM, Nokia, and Motorola), primarily targeted for mobile devices like PDAs and smart phones.
The design of eSWT is different from its cousin SWT in terms of platform-independence. SWT uses the platform-independent approach by trying to keep the native code as simple as possible to increase portability among operating systems. The problem is that portability and performance are competing issues, so eSWT decided on another approach: the Universal Graphics Layer (UGL), which still preserves the Java Native Interface (JNI) on the native tool kit implementation. But, instead of acting as a 1:1 JNI wrapper, UGL tries to keep the native implementation as close as possible, only requiring the information to callback through JNI. eSWT’s approach sacrifices portability since the native tool kit completely depends on what graphics system is used, but this approach increases performance dramatically (a major concern in mobile devices).