Question

I have multiple enums in my code:

public enum First { a, b, c, d; }

public enum Second { e, f, g; }

I want to have one method that checks to see if a value is present in any enum using valueOf() without writing one for each enum type. For example (this code does not run):

public boolean enumTypeContains(Enum e, String s) {
    try {
        e.valueOf(s);
    } catch (IllegalArgumentException iae) {
        return false;
    }
    return true;
}

Usage:

enumTypeContains(First,"a"); // returns true
enumTypeContains(Second,"b"); // returns false

Any ideas on how to do something like this?

Answer 1

Here is your solution:

public static boolean contains(Class<? extends Enum> clazz, String val) {
   Object[] arr = clazz.getEnumConstants();
   for (Object e : arr) {
      if (((Enum) e).name().equals(val)) {
         return true;
      }
   }
   return false;
}

It gets all of the enum’s vaules and checks to see if it has a value that shares a name with the parameter you passed in. If so, then it returns true, otherwise it returns false.

This has been tested and works. Test code:

public class Test {
   public static void main(String[] args) {
      System.out.println(contains(Haha.class, "Bad"));
      System.out.println(contains(Haha.class, "Happy"));
      System.out.println(contains(Haha.class, "Sad"));
   }

   static enum Haha {
      Happy, Sad;
   }
}

Prints:

false
true
true