Different output after execution main class

Question

public class Main {
    public static void main(String[] args){
        System.out.println(X.Y.Z);
    }
}

class X {
    static class Y {
        static String Z = "Result 1";
    }
    static C Y = new C();
}

class C {
    String Z = "Result 2";
}  

Sometime output is "Result 1" and sometime output is "Result 2". Can you explain why?

I am using JDK 1.6_33.

Answer 1

This is Java Puzzler #68 - it should always print Result 2. Quote:

It turns out that there is a rule that governs program behavior under these circumstances. When a variable and a type have the same name and both are in scope, the variable name takes precedence [JLS 6.5.2]. The variable name is said to obscure the type name [JLS 6.3.2]. Similarly, variable and type names can obscure package names. This rule is indeed obscure, and any program that depends on it is likely to confuse its readers.