CODEWITHSUNDEEP
javaclassenums
Joel Shemtov
Joel Shemtov

Reputation: 3078

Listing values of unknown enum

Say we have a Class object. Name it cls.

Now cls.isEnum() returns true

What a joy!!! Could I please have the values listed to me? (one sugar, no milk)

Upvotes: 9

Views: 4375

Answers (3)

Ron Tuffin
Ron Tuffin

Reputation: 54619

getEnumConstants() a method of the Class object returns an array of Objects

public static enum E {
    A, B, C, D;
}

public static void main(String[] args) {
    Class c = E.class;
    for(Object b:c.getEnumConstants())
    {
        System.out.println(b);
    }
}

Prints:

A
B
C
D

Upvotes: 9

polygenelubricants
polygenelubricants

Reputation: 383746

You can use EnumSet.allOf(Class<E>), where <E extends Enum<E>>

Given:

public static enum Alphabet {
    A, B, C, D;
}

You can write:

    for (Enum<?> e : EnumSet.allOf(Alphabet.class)) {
        System.out.println(e);
    }
    // A, B, C, D

Upvotes: 4

Manuel Selva
Manuel Selva

Reputation: 19050

The following main:

public class GetEnumFields {

public static enum Enum {

    A, B, C, D;
}

public static void main(String[] args) {

    Enum a = Enum.A;
    Field[] declaredFields = a.getClass().getDeclaredFields();
    for (int i = 0; i < declaredFields.length; i++) {
        System.out.println(declaredFields[i]);
    }
}

}

prints: 

public static final GetEnumFields$Enum GetEnumFields$Enum.A
public static final GetEnumFields$Enum GetEnumFields$Enum.B
public static final GetEnumFields$Enum GetEnumFields$Enum.C
public static final GetEnumFields$Enum GetEnumFields$Enum.D
private static final GetEnumFields$Enum[] GetEnumFields$Enum.ENUM$VALUES

Upvotes: 2

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