Use Java Enums to Model Finite States

What is an enum in Java, and why is it useful when programming a system with a finite set of states? Explain how an enum improves the representation and what additional logic is still needed to enforce valid state transitions. ### Constraints & Assumptions - Discuss Java enum types rather than integer constants in another language. - You may choose a small illustrative state machine, but its states and transitions are practice examples. - Distinguish a valid state value from a valid transition between two states. ### Clarifying Questions to Ask - Are the states fixed at compile time, or must new states be added dynamically? - Should the example emphasize state representation or transition behavior? ```hint A variable can hold a valid enum constant while the transition that produced that value is still illegal for the application. ``` ### What a Strong Answer Covers Explain named enum instances, type safety, readable comparisons, and the ability to associate behavior with states. Show why finite-state code benefits, identify where transition validation belongs, and discuss the limits of enums when states or their behavior are not fixed. ### Follow-up Questions - Would you persist a state's `ordinal()` as a database identifier? Why or why not? - Does using an enum automatically make state updates thread-safe? - When might a richer state-object design be preferable?