Java: How to check if an object is an instance of a non-static inner class, regardless of the outer object?

Question

If I have an inner class e.g.

class Outer{
    class Inner{}
}

Is there any way to check if an arbitrary Object is an instance of

Answer 1

o instanceof Outer.Inner gives false when o is an instance of an Inner of any Outer other than the one you're calling it from.

This doesn't happen for me - I get true for o instanceof Inner regardless of which particular enclosing instance of Outer the o belongs to:

class Outer {
  class Inner {}

  void test() {
    // Inner instance that belongs to this Outer
    Inner thisInner = new Inner();

    // Inner instance that belongs to a different Outer
    Outer other = new Outer();
    Inner otherInner = other.new Inner();

    // both print true
    System.out.println(thisInner instanceof Inner);
    System.out.println(otherInner instanceof Inner);
  }

  public static void main(String[] args) {
    new Outer().test();
  }
}

Tested with both Java 6 and 7.