The Java Editor example demonstrates the standard features available for custom text editors. It also shows how to register an editor for a file extension (in this case .jav) and how to define a custom Document provider for use by that editor. This example is only for demonstration purposes.
The Abstract Syntax Tree is the base framework for many powerful tools of the Eclipse IDE, including refactoring, Quick Fix and Quick Assist. The Abstract Syntax Tree maps plain Java source code in a tree form. This tree is more convenient and reliable to analyse and modify programmatically than text-based source. This article shows how you can use the Abstract Syntax Tree for your own applications.
The Eclipse Platform is an open and extensible platform. This article explains in detail how the Workbench can be extended to add new actions and provides guidance to the plug-in developers on how they can design for extensibility.