What is the use of enumeration without an instance?

Question

I read and implemented the script through enum. I realized that we can create an enumeration without any instance. What is the practical use of such an Enum ? Secondly, Enum can also implement an interface, but obviously cannot extend the class, since it already extends the Enum class. What are the practical benefits of creating Enum without instances? Ben

Answer 1

Zero-member enumerations are actually a utility-class idiom used by a particular segment of the Java community (primarily Peter Lawrey ). They are the most concise and possibly the cleanest way to ensure that a class cannot be created or subclassed.

Naturally, you will not have any instance methods in such an enumeration; only static.

Answer 2

Enum are reference types such as class or interfaces . This means that you can adapt the principle well, the program for the interface, and not for implementation . "

Answer 3

enum members are not necessarily committed to the end of the universe. You can add new members without breaking binary compatibility. Therefore, I can imagine that enum is being created to model some concept that has no instances at present, but can be added later.

Is it possible to create an enum for a concept that is known to never have any instances? For example enum NegativeNaturalNumber{} ? Can it serve any purpose in the program? Who knows, we cannot say with certainty.