Enum 활용하여 구조 갖추기

검색 키워드: Enum base method(https://www.google.com/search?sxsrf=AOaemvJL4g6548VoU6uBLDbatDr6DfUr4g:1632889481331&q=Enum+base+method+java&sa=X&ved=2ahUKEwilv_erq6PzAhUYBN4KHdJRC2sQ1QJ6BAgxEAE&biw=1941&bih=1068&dpr=1)
검색된 링크	비고
https://dzone.com/articles/enum-tricks-two-ways-to-extend-enum-functionality	Enum cannot either extend or be extended, Mirror Enum(Enumus library) EnumSet과 EnumMap? It is not always possible to implement method in enum itself because the enum may belong to a third-party library or another team in the company all enum types in Java are singleton by default.
https://howtodoinjava.com/java/enum/enum-tutorial/	concrete methods in enum, abstract methods in enum, enum inheritance.  EnumSet과 EnumMap
https://stackoverflow.com/questions/17820671/enum-base-classes-in-java	Enums cannot extend anything because enums automagically extend class Enum. But Enum can implement methods.
https://www.baeldung.com/java-extending-enums	Enum cannot either extend or be extended Emulate Extensible Enums With Interfaces Emulate Extending the Constants Extending an Enum Without Changing the Code