8.1. MX List genealogy

As discussed in chapter 2, Flex is a declarative framework for the object-oriented ActionScript 3.0 language, and it’s important to be aware of how objects within the framework are related. When it comes to List-based components in the MX library, the top dogs are the MX ListBase and AdvancedListBase classes (which extend ScrollControlBase, which then subclasses UIComponent). Because these are base classes, you don’t use them directly. Instead, they act as the foundation for the MX List-based controls.

ListBase and AdvancedListBase provide support for attributes such as width and height, how many rows are to be displayed, and the basic display of information. They also handle user interactions by triggering events (for example, an item being selected). The diagram in figure 8.1 demonstrates these relationships.