How to get number of possible item of an Enum?

Is there a builtin way to get the number of items of an Enum with something like Myenum.length,

Or do I have to implement myself a function int size() hardcording the number of element?

Answer

Yes you can use the Enum.values() method to get an array of Enum values then use the length property.

public class Main {
    enum WORKDAYS { Monday, Tuesday, Wednesday, Thursday, Friday; }

    public static void main(String[] args) {
        System.out.println(WORKDAYS.values().length);
        // prints 5
    }
}

http://ideone.com/zMB6pG