Can an object referencing itself inside double-brace initialization not give a NPE?

Question

I have this little piece of code here, which always will throw a NPE:

public class Test1 {
    private final static Object OBJECT = new Object() {{
        System.out.println("OBJECT.toString() = " + OBJECT.toString());
    }};
    public static void main(String[] args) { }
}

Are there ways though that OBJECT can be initialized in the instance initialization block? Or will every possible reference to OBJECT in the instance initialization block always throw a NPE?

For those Fastest-Gun-In-The-Wests, read this: No, I am not asking you to solve my bug. This is a simplified piece of code I've seen somewhere and which to my surprise does not give a null warning in either Eclipse or Netbeans, which I would expect it to give.

Answer 1

Double brace initialisation is just an anonymous inner class with instance initialiser. Therefore the rules governing creating objects apply.

NPE is a Runtime Exception so an IDE uses heuristics to find the culprits rather than the rigour and certainty provided by static typing, declared exceptions, and static code analysis. Here it would have to execute the code in order to find runtime issues.

What is happening is this: a static member is being initialised by assigning to it anonymous inner class. Constructor of the inner class has finished as this is the rule for instance initializers. However the reference is assigned only after initialisers have finished, which they have not by the time you try to dereference OBJECT.

Seems like a very circular explanation, but that's because what is happening is circular referencing ;)