Ordering enum values

Question

I was wondering if there is any way of ordering enum for different classes. If for example, I have a fixed group of chemicals which react in different ways to other chemical

Answer 1

Suppose you have an enum of elements:

enum Elements {Oxygen, Hydrogen, Gold}

and you would like to sort them in a given order, then I can do:

Elements[] myElements = Elements.values();
Arrays.sort(myElements, new ElementComparator());

where ElementComparator can be something like:

public class ElementComparator implements java.util.Comparator {
    public int compare(Elements left, Elements right){
        return right.compareTo(left); //use your criteria here
    }
}

The nature of the ordering criteria is not clear in your question. It seems like it's about something related to chemical reactions. I suppose that criteria should go in the Comparator to decide which enum element is bigger than the other given a chemical reaction.