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November 2000



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Sorry for the long message !! revert back if I have got your question wrong

Posted by Sridhar Visvanath on November 17, 2000 at 1:11 AM

import mylib.*;

class Client
public static void main(String[]args)
InDirectAccess ia = new InDirectAccess();
/* try uncommenting the following line and you will get a compile-time error
that you can't access the class because DirectAccess is not a public class and
a package class and hence available only within its package.
The public int in DirectAccess carries any meaning
only if the class to which it belongs , in this case DirectAccess , has a public access,
which is not true as DirectAccess is available only within it's package mylib

The access specifiers for classes supersedes that of its variables.

When you cannot enter a country (say USA) how will you be able to
enter a city (say Buffalo) in that country.

When you cannot enter a class (DirectAccess) how will you be able to
access it variable (Integer var ) in that class.

You can say that Buffalo is inaccessible inside USA even though the other parts of the
USA are accessible by saying that Buffalo is private .

similarly had your class DirectAccess been available to the Client , then
you can prevent them from accessing the Integer var by making that var private

You can however access a ref obj to the DirectAcces from the InDirectAccess because
the IndirectAccess is public and the obj var is not private / protected / default
but public.


//DirectAccess da = new DirectAccess();

> //
> package mylib;

> class DirectAccess {
> public Integer var = new Integer(10);
> }

> ------------------------------------------------------

> //
> package mylib;

> public class IndirectAccess {
> public DirectAccess obj= new DirectAccess();
> }

> ------------------------------------------------------

> //
> import mylib.*;

> class client {
> public static void main(String arg[]) {
> IndirectAccess ia = new IndirectAccess();
> System.out.println(ia.obj.var);
> }
> }

> ------------------------------------------------------

> compile, got complaint:

> The type mylib.DirectAccess to which the member var belongs is
> not accessible from class client.
> System.out.println(ia.obj.var);
> ^
> 1 error


> in class DirectAccess: wheather var is public or default doesn't make any difference, why wouldn't compiler
> complain about this, because if there is no way for any class outside mylib package to access "var", then
> its modifier "public" only cause confusion.

> Thanks,
> John


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