12.1. Wallpaper Diagrams

The classic novice class diagram displays all classes, attributes, operations, relationships, and dependencies for a system. As the number of classes grows, the diagram becomes huge and unmanageable. Imprudent reverse engineering drags in clutter. Figure 12-1 diagrams just a very small part of the Java Abstract Windowing Toolkit (AWT). You will not be able to read the diagram because it normally prints as an unwieldy nine pages. You're paying for the paper, so the diagram is shown here in a greatly condensed form.

Effective writers convey ideas through language constructs: sentences and paragraphs organize text, details reinforce ideas, and true but irrelevant facts are omitted. Modelers desiring to convey an idea—be it a structural overview, a pattern implementation, a detailed subsystem, or the detailed context of one class—must also use economy and focus. Figure 12-1 has neither economy nor focus. The diagram throws a mass of insignificant detail at readers, leaving the burden of understanding on them. It is a false economy to think that one diagram can present all the information of a multidimensional model.