Adding generics causes error in code

Question

Hi,
I have written a method to see if a supplied array of enums contains the specified enum.
The first version of the code had warnings:-
public static boolean enumInList(Enum type, Enum[] typesList) {
          if (type == null) {
               return (true);
          for (Enum enum1 : typesList) {
               if ((type.compareTo(enum1) == 0)) {
                    return (true);
          return (false);
     }...the warnings were 'Enum is a raw type. References to generic type Enum<E> should be parameterized'
When I removed these the code looks as follows:-
public static boolean enumInList(Enum<?> type, Enum<?>[] typesList) {
          if (type == null) {
               return (true);
          for (Enum<?> enum1 : typesList) {
               if ((type.compareTo(enum1) == 0)) {
                    return (true);
          return (false);
     }The warnings disappeared but the 'compareTo' now as a serios error which says:-
The method compareTo(capture#2-of ?) in the type Enum<capture#2-of ?> is not applicable for the arguments (Enum<capture#3-of ?>)
So by removing the warnings I have made the code worse but removing the warnings is the correct thing to so.
Therefore is there a way i can write to code to have both no warnings or errors but without having to resort to using annotation to suppress the warnings.
Thanks,
Dave.

Answer 1

the warning message is telling you that the enum compareTo method is expecting an enum of the same type, whereas your method definition specifies two enums of potentially different types. you should need to introduce a generic type indicating that the two enum types are equivalent:
public static <E extends Enum<E>> boolean enumInList(Enum<E> type, Enum<E>[] typesList)this will indicate that you expect 2 enum params with the same type.
that said, i have no idea why you are using compareTo to test for equality. either use "type.equals(enum1)", or better yet, "type == enum1" (which has the benefit of being null-safe).