How to pass multiple enum types as method arguments and then call common methods on them?

Question

Our issue is like this: We want to pass different enum types to a method and call the values() method on the type.

public enum Testing {
    A, B, C, D
}

public enum Retesting {
    E, F, G, H
}

public static Object[] getValues(Enum e) {
    return e.values(); // ! Compilation Error
}

public static void main(String[] args) {
    Testing t = Testing.A;
    getValues(t);
}

Does anyone know if how something like this should be achieved or if it's possible at all?

Thank you

It's not clear what problem you want to solve. Can you explain why you need this? — Puce, Mar 13 '12 at 16:30
possible duplicate of [Getting all the enum values from enum value](http://stackoverflow.com/questions/2269803/getting-all-the-enum-values-from-enum-value) — Brian Roach, Mar 13 '12 at 16:34
It's possible. look at my answer. But `Enum e` here means that `e` is an instance of some enum, say `Testing.A`. Method `getValues(Class extends Enum> e)` would be more correct. Than you could write `e.getEnumConstants()`. — korifey, Mar 13 '12 at 16:36
@korifey - Your answer is correct; you have to get the values from the class itself. This has already been asked and answered on SO which is why I voted to close as dup. — Brian Roach, Mar 13 '12 at 16:38

score 7 · Accepted Answer · edited Apr 16 '12 at 11:55

7

Try using:

e.getClass().getEnumConstants()

edited Apr 16 '12 at 11:55

answered Mar 13 '12 at 16:32

korifey

3,379
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Matt McHenry · Answer 2 · 2012-03-13T16:37:11.483

0

Here is a solution using reflection. But I like @korifey's answer better. :)

@SuppressWarnings("unchecked")
public static <T extends Enum<T>> T[] getValues(Class<T> e) throws IllegalArgumentException, SecurityException, IllegalAccessException, InvocationTargetException, NoSuchMethodException {
    return (T[]) e.getMethod("values").invoke(null);
}

public static void main(String[] args) throws IllegalArgumentException, SecurityException, IllegalAccessException, InvocationTargetException, NoSuchMethodException {
    System.out.println(Arrays.asList(getValues(Testing.class)));
}

edited Mar 13 '12 at 16:37

answered Mar 13 '12 at 16:31

Matt McHenry

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64

There's no such method as `values` in `Enum`. That would be the first problem the OP has ... – Brian Roach Mar 13 '12 at 16:35

score 0 · Answer 3 · answered Mar 13 '12 at 16:36

Both @korifey and @Matt McHenry are right (+1 to each one). I personally think that in your case korifey's way is preferable.

I just wanted to add that your method signature may be:

getValues(Enum e) { .... }

because all enums are ordinary classes that extend class Enum;

How to pass multiple enum types as method arguments and then call common methods on them?

3 Answers3