Java - create enums with dot notation

Question

I need to have enums with dot notation like this WEATHER.SUNNY since they represent topics using wildcards. I know that this is not possible because enums need to be valid identifiers.

here someone suggest to overwrite the toString method but I dont really get how that is meant. However, is it still possible to do so?

Answer 1

You can definitely do what @Stefan suggests, but this might be a good use case for attaching a field to your enum values:

public enum Topic {
    SUNNY("WEATHER.SUNNY"), CLOUDY("WEATHER.CLOUD"), ...

    String notation;

    Topic(String notation) {
        this.notation = notation;
    }

    public String getNotation() { return notation; }
}

And then you can invoke Topic.SUNNY.getNotation() .

Answer 2

Sample code that shows the idea of overriding toString:

public class Test {

enum Weather { Sunny, Cloudy;

    @Override
    public String toString() {
        return "WEATHER." + super.toString().toUpperCase();
    }

};

public static void main(String[] args) {
    System.out.println(Weather.Sunny);
}
}

Output: WEATHER.SUNNY

Answer 3

There is no problem with defining enum that has a capitalized name. It would be not consistent with Java naming conventions, but it works.

enum WEATHER {
    SUNNY, CLOUDY;
}

Then you would use like this:

WEATHER weather = WEATHER.SUNNY