Question

I have a problem, I need to resolve type of class which replaced the generic type parameter. Here is the code:

public class EnumSetPlay {

    private enum SomeEnum {ONE, TWO}

    private static class Test<E extends Enum> {
        private Class<E> clazz = (Class<E>) GenericTypeResolver.resolveTypeArgument(getClass(), Test.class);;

        public void test() {
            for (E element : EnumSet.allOf(clazz))
                System.out.println(element);
        }
    }

    public static void main(String... args) {
        new Test<SomeEnum>().test();
    }
}

I need to get class type SomeEnum.
I trying to use spring GenericTypeResolver class, but I have next error:

error: incompatible types
required: E
found:    Object
where E is a type-variable:
E extends Enum declared in class Test

Answer 1

I don’t think that this is possible due to type erasure, which removes the type information. Some links:

• http://docs.oracle.com/javase/tutorial/java/generics/erasure.html
• Java generics – type erasure – when and what happens
• http://www.angelikalanger.com/GenericsFAQ/FAQSections/TechnicalDetails.html