finner

finner

Enum: Behind the scenes

I’ve never really felt 100% comfortable using the enum type because of my lack of understanding how it is constructed . . .

. . . until now :grin:

Here is how a basic enum might be typically declared.

enum DevTalkForum {
   NEWS,
   CHAT,
   JOURNALS,
   BOOK_ERRATA
}

And here is the class that is constructed behinds the scenes:

final class DevTalkForum extends Enum<DevTalkForum> {

   /**
    *   the type Enum only has 2 simple properties: 
    */
   private DevTalkForum(String name, int ordinal) { 
      super(name, ordinal); 
   }

   /**
    *   each element in the enum is a subclass of the type Enum
    */
   public static final DevTalkForum NEWS = new DevTalkForum("NEWS", 0);
   public static final DevTalkForum CHAT = new DevTalkForum("CHAT", 1);
   public static final DevTalkForum JOURNALS = new DevTalkForum("JOURNALS", 2);
   public static final DevTalkForum BOOK_ERRATA = new DevTalkForum("BOOK_ERRATA", 3);

   /**
     *   all the enum classes are stored in an array
     */
   private static final DevTalkForum[] VALUES = { NEWS, CHAT, JOURNALS, BOOK_ERRATA };
   
   public static DevTalkForum[] values() { 
      return VALUES.clone(); 
   }
   
   public static DevTalkForum valueOf(String name) {
      for (DevTalkForum e : VALUES) 
         if (e.name().equals(name)) return e;
      throw new IllegalArgumentException();
   }
}

Realising how the enum is constructed has helped me understand how to use it correctly.
For example, the toString() of the class can be overridden to provide an alternative string value if you do not want to add another property.

enum DevTalkForum {
    NEWS,
    CHAT,
    JOURNALS,
    BOOK_ERRATA;

    @Override
    public String toString() {
        switch (this) {
            case CHAT:
                return "Chat";
            case JOURNALS:
                return "Journals";
            case BOOK_ERRATA:
                return "Book Errata";
            case NEWS:
            default:
                return "News";
            
        }
    }
}

So now that I feel closer to the enum I think I’m going to try and pop them into my code a bit more often.

Hope this was somehow helpful

Most Liked

AstonJ

AstonJ

Nice one Finner :+1:

Funnily enough, I had to re-read the Enumerable and Enumerator chapter in The Well Grounded Rubyist (which I loved btw) a couple of times as it’s a little harder to grok than some of the other stuff. I’d actually like to read the book again one day as I loved it :smiley:

Where Next?

Popular Backend topics Top

DevotionGeo
For me it’s the semicolon, because I stopped using a semicolon in JavaScript, two other of my favorite languages, Elixir and Go don’t hav...
New
AstonJ
Or which features of current frameworks you use you feel you couldn’t live without?
New
wolf4earth
Serverless has been quite a prevalent topic in our industry in the past few years, and while there are a lot of sceptics, I think it’s sa...
New
bot
Announcing the Error Handling Project Group | Inside Rust Blog. Want to follow along with Rust development? Curious how you might get in...
New
New
First poster: bot
C++: The Good Parts . Jordan DeLong overviews the past, current and near future “good parts” of C++'s functional side through the colore...
New
Exadra37
Finishing my app to take notes on Videos: I am aiming to put it online on my playground by this weekend. Edit: It’s up https://video...
New
mafinar
This is going to be a long an frequently posted thread. While talking to a friend of mine who has taken data structure and algorithm cou...
New
jaeyson
Sorry for the very vague noob question, I really want to ask this: When do we use async or sync code in the context of Elixir? AFAIK gen...
New
mafinar
We always have fun in this forum around this time of the year, discussing the days’ (or yesterdays’) challenges and talking through solut...
New

Other popular topics Top

Devtalk
Hello Devtalk World! Please let us know a little about who you are and where you’re from :nerd_face:
New
ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
New
PragmaticBookshelf
Tailwind CSS is an exciting new CSS framework that allows you to design your site by composing simple utility classes to create complex e...
New
PragmaticBookshelf
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
rustkas
Intensively researching Erlang books and additional resources on it, I have found that the topic of using Regular Expressions is either c...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
New
AstonJ
This is cool! DEEPSEEK-V3 ON M4 MAC: BLAZING FAST INFERENCE ON APPLE SILICON We just witnessed something incredible: the largest open-s...
New
AstonJ
This is a very quick guide, you just need to: Download LM Studio: https://lmstudio.ai/ Click on search Type DeepSeek, then select the o...
New