How to use an enum as one would use an interface?

Question

How can I assign SomeEnum1 or SomeEnum2 to an "enum" which implements SomeInterface? I can't just specify the interface directly as it's a class and not an enum.

I'm sure there is a specify syntactic sugar to make this work but I can't figure it out.

Example:

public class Main {

   public interface SomeInterface {

       public String doSomething();

   }



   public enum SomeEnum1 implements SomeInterface {

      something1;



      @Override

      public String doSomething() {

         return "SomeEnum1";

      }

   }



   public enum SomeEnum2 implements SomeInterface {

      something2;



      @Override

      public String doSomething() {

         return "SomeEnum2";

      }

   }



   public static void main(String[] args) {

      // Works but not polymorphic

      SomeEnum1 e1 = SomeEnum1.something1;

      System.out.println(e1.name() + " " + e1.doSomething());



      // Not an enum

      // SomeInterface e2 = SomeEnum1.something1;

      // System.out.println(e2.name() + " " + e2.doSomething());



      // Bounds mismatch

      // Enum<SomeInterface> e3 = SomeEnum1.something1;

      // System.out.println(e3.name() + " " + e3.doSomething());

   }

}

Answer 1

If you pass the value to a method, you can use generics to restrict the type of SomeInterface by 2 constraints:

public static void main(String[] args) {
    print(SomeEnum1.something1);
}

public static <T extends Enum & SomeInterface> void print(T t) {
    System.out.println(t.name() + " " + t.doSomething());
}

How to use an enum as one would use an interface?

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