Now you know three modular ways of running code as part of the main update loop: you can implement the simpleUpdate() method in the main class, you can add controls to spatials, and you can attach AppState objects.
You can activate or deactivate an individual chunk of behavior by adding or removing a control, or by attaching and detaching an AppState object. You can move whole chunks of the scene graph out of the main simpleInitApp() method, and make them part of an AppState object. For example, a hypothetical OutdoorsAppState object's
initialize() method attaches bright lights and a forest sound loop; its
cleanup() method detaches what the AppState object brought, so you can switch to the IndoorsAppState object, which itself brings dim fluorescent lights and a factory sound loop. This modularization helps you keep your code reusable and maintainable.
Since your game behavior interacts, you have to be aware of the order in which its pieces execute during...