It’s been noted [e.g. 1] that showing the static class structure is important in teaching materials and tools. BlueJ, for instance, places a lot of emphasis on this.
The JAKE IDE dynamically compiles a class diagram as classes are added to the JAKE program. Every program starts with a default class diagram that shows all the classes in the main JAKE package: World, Mover, Robot, and so on.
The diagram uses a variant UML notation, with arrows for generalisations. The classes themselves, however, don’t have methods or attributes. Instead, they’re represented by a box with an icon and caption.
The class diagram is shown alongside the main program editors in JAKE, but it can also be maximised. In later versions, the maximised diagram could be printed through the File menu. The diagram window automatically scrolls if the diagram becomes too large, but JAKE’s simple class structure makes this unlikely.
 Börstler, J., Hall, M. S., Nordström, M., Paterson, J., Sanders, K., Schulte, C. and Thomas, L. An Evaluation of the State-of-the-Art of Object-Oriented Example Programs in Introductory Programming Textbooks. In inroads SIGCSE Bulletin. (July 6-9 2009). ACM New York, NY, USA, , 2009, 126-143.