Groups > comp.lang.java.programmer > #29669

Accessibility of suBclass-fields from suPERclass (reflection)

From	Andreas Leitgeb <avl@auth.logic.tuwien.ac.at>
Newsgroups	comp.lang.java.programmer
Subject	Accessibility of suBclass-fields from suPERclass (reflection)
Date	2014-08-15 00:58 +0000
Organization	A noiseless patient Spider
Message-ID	<slrnluqmpu.fp3.avl@login.logic.tuwien.ac.at> (permalink)

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It is clear to me, that a class may need to protect its fields from direct
access by subclasses or unrelated classes, mostly because the developer of
a base class doesn't always know all derived or unrelated classes ahead of
time.

Otoh, someone who derives a class, or even does it in a statement block of
their own code, obviously can be expected to "know" and "trust" those
classes he derives or includes derivatives of.

E.g., someone writing this:
   public class Outer extends Base {
      static {
         class Inner extends Base { ... }
      }
   }
had better know/trust "class Base", and have no need to have his code
protected from reflective examination by class Base.

Now, apparently, the designers of Java felt differently, and to examine (by
use of reflection) the fields of "Inner" from within Base's code, Base has to
jump an extra hoop (namely calling setAccessibility(true)), requesting access
from an eventually installed SecurityManager.

Surprisingly (or not), that extra hoop is not required to examine "Outer"'s
fields from within "Base".  Also, it is not possible to mark an inner class
as public in an attempt to grant accessibility of "Inner" to "Base".

It makes no sense to me, why there is any defense-mechanism at all against 
field access from code within a known Baseclass.

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Thread

Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-15 00:58 +0000
  Re: Accessibility of suBclass-fields from suPERclass (reflection) Lew <lewbloch@gmail.com> - 2014-08-15 15:20 -0700
    Re: Accessibility of suBclass-fields from suPERclass (reflection) Steven Simpson <ss@domain.invalid> - 2014-08-16 00:11 +0100
      Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-16 00:10 +0000
  Re: Accessibility of suBclass-fields from suPERclass (reflection) Arne Vajhøj <arne@vajhoej.dk> - 2014-08-15 23:26 -0400
    Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-16 08:46 +0000
      Re: Accessibility of suBclass-fields from suPERclass (reflection) Robert Klemme <shortcutter@googlemail.com> - 2014-08-16 12:27 +0200
        Re: Accessibility of suBclass-fields from suPERclass (reflection) "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-16 13:37 +0100
          Re: Accessibility of suBclass-fields from suPERclass (reflection) Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-16 09:47 -0400
          Re: Accessibility of suBclass-fields from suPERclass (reflection) Robert Klemme <shortcutter@googlemail.com> - 2014-08-17 13:19 +0200
        Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-16 22:37 +0000
          Re: Accessibility of suBclass-fields from suPERclass (reflection) Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-16 20:22 -0400
            Re: Accessibility of suBclass-fields from suPERclass (reflection) Josip Almasi <joe@vrspace.org> - 2014-08-17 12:51 +0200
              Re: Accessibility of suBclass-fields from suPERclass (reflection) Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-17 07:54 -0400
                Re: Accessibility of suBclass-fields from suPERclass (reflection) "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2014-08-17 13:44 +0100
                Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-17 17:42 +0000
                Re: Accessibility of suBclass-fields from suPERclass (reflection) Arne Vajhøj <arne@vajhoej.dk> - 2014-08-18 20:45 -0400
                Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-20 18:47 +0000
                Re: Accessibility of suBclass-fields from suPERclass (reflection) Josip Almasi <joe@vrspace.org> - 2014-08-18 17:19 +0200
            Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-17 18:04 +0000
              Re: Accessibility of suBclass-fields from suPERclass (reflection) Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-17 15:24 -0400
                Re: Accessibility of suBclass-fields from suPERclass (reflection) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-17 21:35 +0000
      Re: Accessibility of suBclass-fields from suPERclass (reflection) Josip Almasi <joe@vrspace.org> - 2014-08-16 12:31 +0200
      Re: Accessibility of suBclass-fields from suPERclass (reflection) Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-08-16 10:51 -0400
      Re: Accessibility of suBclass-fields from suPERclass (reflection) Arne Vajhøj <arne@vajhoej.dk> - 2014-08-16 11:00 -0400

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