Warnings

[John Neffenger]

On 12/4/22 8:22 AM, John Hendrikx wrote:
> - Avoiding indirect access to static methods and fields
> 
>         class A { static final int ONE = 1; }
>         class B { }
>         class C extends B {
>              int one = ONE;  // unqualified access to A.ONE
>         }

Did you mean the following?

     class B extends A { }

There's a related trap in this category: inaccessible members can be 
unintentionally made public by an intermediate subclass. For example:

     package pkg1;
     interface A { static final int ONE = 1; } // ONE has package access

     package pkg1;
     public class B implements A { } // ONE is now public in B

     package pkg2;
     import pkg1.B;
     class C extends B {
         int one = ONE; // ONE is accessible in pkg2.C
     }

Through this chain, members with package access (not just constants) can 
inadvertently end up in a public API. There are 423 occurrences of this 
in the Java API. There's a fix in JDK 20 that should let us find them in 
the JavaFX API, too. I don't think there's much we can do about it 
except be aware of them.

I was really surprised by this, but see the classes in the 'pkg1' and 
'pkg2' directories below for an example that you can compile and run:

https://github.com/openjdk/jdk/tree/master/test/langtools/jdk/javadoc/doclet/testIndexInherited

John