How do Java method annotations work in conjunction with method overriding?

annotations, inheritance, java, overriding

Solution

Copied verbatim from http://www.eclipse.org/aspectj/doc/released/adk15notebook/annotations.html#annotation-inheritance:

Annotation Inheritance

It is important to understand the rules relating to inheritance of annotations, as these have a bearing on join point matching based on the presence or absence of annotations.

By default annotations are not inherited. Given the following program

        @MyAnnotation
        class Super {
          @Oneway public void foo() {}
        }

        class Sub extends Super {
          public void foo() {}
        }

Then `Sub` does not have the `MyAnnotation` annotation, and `Sub.foo()` is not an `@Oneway` method, despite the fact that it overrides `Super.foo()` which is.

If an annotation type has the meta-annotation `@Inherited` then an annotation of that type on a class will cause the annotation to be inherited by sub-classes. So, in the example above, if the `MyAnnotation` type had the `@Inherited` attribute, then `Sub` would have the `MyAnnotation` annotation.

`@Inherited` annotations are not inherited when used to annotate anything other than a type. A type that implements one or more interfaces never inherits any annotations from the interfaces it implements.

Problem

I have a parent class `Parent` and a child class `Child`, defined thus: ``` class Parent { @MyAnnotation("hello") void foo() { // implementation irrelevant } } class Child extends Parent { @Override foo() { // implementation irrelevant } } ``` If I obtain a `Method` reference to `Child::foo`, will `childFoo.getAnnotation(MyAnnotation.class)` give me `@MyAnnotation`? Or will it be `null`? I'm interested more generally in how or whether annotation works with Java inheritance.

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