Why isn't the Java compiler (specifically its parser) able to understand this statement

Question

I have the following two classes (in two separate files).

public class Foo
{
    public static class A
    {
        public static final boolean FLAG = false;
    }

    public final A A = new A();
}


public class Bar
{
    void method()
    {
         if (Foo.A.FLAG)  <<<< this is giving "Cannot make static ref to non-static field
            // do something
           ;
    }
}

My question is, why isn't the compiler able to recorgnise that by Foo.A, I meant the class A, not the member, which also happens to be named A?

Answer 1

This is called obscuring, an obscure feature/limitation of Java

A simple name may occur in contexts where it may potentially be interpreted as the name of a variable, a type, or a package. In these situations, the rules of §6.5 specify that a variable will be chosen in preference to a type, and that a type will be chosen in preference to a package. Thus, it is may sometimes be impossible to refer to a visible type or package declaration via its simple name. We say that such a declaration is obscured.

If the variable A was static, it would compile since you can can access static members on object references.

---

Also FLAG hasn't been initialized.

Answer 2

Some ways to access the flag:

<Foo_A extends Foo.A> void test1()
{
    if(Foo_A.FLAG)
        ;
}

void test2()
{
    class Foo_A extends Foo.A{}
    if(Foo_A.FLAG)
        ;
}

-------------------------------------
import pkg.Foo.A;

public class Bar
{
    void test3()
    {
        if(A.FLAG)
            ;
    }
}

in these contexts, "Foo.A" can only be interpreted as a type, not a variable.