CODEWITHSUNDEEP
javareflectionenumsjaxb
JavaBeast
JavaBeast

Reputation: 836

Getting enum value with reflection

I am trying to loop through and print all the ENUM values of a given Enum Class at run time. But I can only seem to return the constants associated to the values. Most solutions point to using getEnumConstants(), values(), or valueOf(), but I have been unable to get them to work as desired.

The closest questions I could find are Get value of enum by reflection and how-to-get-all-enum-values-in-java, but they apparently are different enough that the solutions did not fit my requirements. Below is the code I have tried and the ENUM class which is auto generated and immutable:

Class cls = Class.forName("TestEnum");
for (Object obj : cls.getEnumConstants()) 
{
    System.out.println(obj.toString()); //prints TEST___A (not TEST_1)
    System.out.println(Enum.valueOf(cls, obj.toString()));  //prints TEST___A (not TEST_1)
}

and the ENUM:

@XmlType(name = "TestEnum")
@XmlEnum
public enum TestEnum {

    @XmlEnumValue("TEST_1")
    TEST___A("TEST_1"),
    @XmlEnumValue("TEST_2")
    TEST___B("TEST_2");
    private final String value;

    TestEnum(String v) {
        value = v;
    }

    public String value() {
        return value;
    }

    public static TestEnum fromValue(String v) {
        for (TestEnum c: TestEnum.values()) {
            if (c.value.equals(v)) {
                return c;
            }
        }
        throw new IllegalArgumentException(v);
    }

desired output:

TEST_1
TEST_2

Actual output:

TEST___A
TEST___B

Perhaps this would be easier if I understood what these auto generated classes are doing and what they are for?

Upvotes: 8

Views: 14742

Answers (2)

JavaBeast
JavaBeast

Reputation: 836

Finally got it:

Class cls = Class.forName("TestEnum");
for (Object obj : cls.getEnumConstants()) {
   try {
       Method m = cls.getMethod("value", null);
       System.out.println(m.invoke(obj, null));
   } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException ex) {
       System.out.println("could not find enum");
   }
}

Upvotes: 13

OldCurmudgeon
OldCurmudgeon

Reputation: 65811

Perhaps something like this (no reflection necessary):

enum MyEnum {
    TEST____1("TEST_1"),
    TEST____2("TEST_2");

    final String value;

    MyEnum(String value) {
        this.value = value;
    }

    public String getValue() {
        return value;
    }
}

public void test(String[] args) {
    for (MyEnum e : MyEnum.class.getEnumConstants()) {
        System.out.println(e.toString() + " - " + e.getValue());
    }
}

or even

enum MyEnum {
    TEST____1("TEST_1"),
    TEST____2("TEST_2");

    final String value;

    MyEnum(String value) {
        this.value = value;
    }

}

public void test(String[] args) {
    for (MyEnum e : MyEnum.class.getEnumConstants()) {
        System.out.println(e.toString() + " - " + e.value);
    }
}

Upvotes: 0

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