access to another package superclass protected constructor is permitted

Name: ngC57085 Date: 06/24/97



Java Virtual Machine permits to use protected constructors of the superclass
from another package by an invocation of the method newInstance of class Class.


JLS (6.6.2) says:

"
A protected member or constructor of an object may be accessed from outside
the package in which it is declared only by code that is responsible for the
implementation of that object. Let C be the class in which a protected member
or constructor is declared and let S be the subclass of C in whose
declaration the use of the protected member or constructor occurs. Then:
            . . .
   Otherwise, if an access is of a protected constructor:
            . . .
      If the access is by an invocation of the method newInstance of
      class Class, then the access is not permitted.
"

Next test shows that the access to protected constructor by an invocation of the
method newInstance of class Class is permitted when the class where this
constructor is used and the class where it is declared are in the different
packages.


> jac113 -d . name06801c.java
> jac113 -d . name06801.java
> ja113 -verify name06801.name06801
25
failed
>
------------------------name06801c--------------
package name06801.name06801a;

public class name06801c {
   protected name06801c (int a) { n = a; }
   protected name06801c () { n = n*n; }
   public int n = 5;
}
--------------------------------------
------------------------name06801--------------
package name06801;

import java.io.PrintStream;
import name06801.name06801a.name06801c;

public class name06801 {
  public static void main(String argv[]) {
     System.exit(run(argv, System.out) + 95/*STATUS_TEMP*/);
  }
  public static int run(String argv[],PrintStream out) {
     name06801d d = new name06801d ();
     if ( ! d.check(out) ) {
        out.println("failed");
        return 2/*STATUS_FAILED*/;
     }
     return 0/*STATUS_PASSED*/;
  }
}

class name06801d extends name06801c {
   name06801d () { super(4); }
   name06801c c1;
   Class cl;
   boolean check (PrintStream out) {
      try {
         cl = java.lang.Class.forName ("name06801.name06801a.name06801c");
      }
      catch (ClassNotFoundException e) {
         out.println(e);
         return false;
      }
      try {
         c1 = (name06801c)cl.newInstance ();
      }
      catch (Exception e) {
         out.println(e);
         return true;
      }
      out.println(c1.n);
      return false;
   }
}
--------------------------------------



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