Java – find all possible enum combinations

Is there an effective way to find all possible combinations between multiple enumerations in Java?

Consider the following three enumerations –

public enum EnumOne {
   One ("One"),OneMore ("OneMore");
}

public enum EnumTwo {
   Two ("Two"),}

public enum EnumThree {
   Three ("Three"),ThreeMore ("ThreeMore");
}

I want the output to produce all possible combinations between these multiple enumerations, that is

{EnumOne.One,EnumTwo.Two,EnumThree.Three},{EnumOne.One,EnumThree.ThreeMore},{EnumOne.OneMore,EnumThree.ThreeMore}

I hope to find an effective way to deal with it

thank you

Solution

The complexity of the algorithm is O (nxmxk.... XZ). If I am wrong, I don't know whether it is an "effective way" I use it as a backtracking solution

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class ProductEnums {

    public enum EnumOne {
        One,OneMore;
    }

    public enum EnumTwo {
        Two,}

    public enum EnumThree {
        Three,ThreeMore;
    }

    public static void main(String[] args) {
        // pass each values in enums
        List a = product(EnumOne.values(),EnumTwo.values(),EnumThree.values());
        System.out.println(a);
    }

    public static List<List<Enum>> product(Enum[]... enums) {
        return product(new ArrayList<>(Arrays.asList(enums)));
    }

    public static List<List<Enum>> product(List<Enum[]> enums) {
        if (enums.isEmpty()) {
            //Trivial case of recursive function
            return new ArrayList<>();
        }
        //remove first element
        Enum[] myEnums = enums.remove(0);
        List<List<Enum>> out = new ArrayList<>();
        for (Enum e : myEnums) {
            //call recursive
            List<List<Enum>> list = product(enums);
            for (List<Enum> list_enum : list) {
                //for each list get from recursion adding element e
                list_enum.add(0,e);
                out.add(list_enum);
            }
            if(list.isEmpty()){
                List<Enum> list_enum = new ArrayList<>();
                list_enum.add(e);
                out.add(list_enum);
            }
        }
        enums.add(0,myEnums); //Backtraking
        return out;
    }
}

result