Inner classes question ..

[uddipan@xxxxxxxxxxxxxxxx (Uddipan Bagchi)]

The story behind it goes as follows.
In the first example, out is an *instance* variable. And, as we all know
instance variables are accessible by all inner and anonymous classes.
So, u'r code compiles all right.
In the second example, out is a local variable with block scope
(accessible only in the block of code in method machmal()). Such
*non-instance* (and *non-class*) variables must be declared final to be
accessible within any classes declared in the same scope.
Note : An interesting fall-out of the final declaration is that you will
not be able to assign any value to out (like 99 or -100) after that.

Frank Gruetzmacher wrote:

> Dear all !
>
> I don't want
> to borow anybody
> in this honest list,
> but I wonder about hsi
> difference ..
>
> This example compiles fine ..
>
> public class A3  {
>    int out=0;
>    void machmal( final int x ) {
>
>        class DEBUG {
>            void print() {
>                   System.out.println("X ist :"+x);
>                   System.out.println("Out ist :"+out);
>            }
>         }
>
>         DEBUG d=new DEBUG();
>         if ( x > 0 ) {
>            out=99;
>         } else {
>            out=-100;
>     }
>         d.print();
>   }
>
>   public static void main(String[] args) {
>     A3 atest= new A3();
>
>     atest.machmal(7);
>     atest.machmal(-7);
>
>   }
>
> ... but this not :
>
> public class A3  {
>    //int out=0;
>    void machmal( final int x ) {
>
>         int out=0: // ??? it must be final now .. but why ?
>
>         class DEBUG {
>            void print() {
>                   System.out.println("X ist :"+x);
>                   System.out.println("Out ist :"+out);
>            }
>         }
>
>         DEBUG d=new DEBUG();
>         if ( x > 0 ) {
>            out=99;
>         } else {
>            out=-100;
>     }
>         d.print();
>   }
>
>   public static void main(String[] args) {
>     A3 atest= new A3();
>
>     atest.machmal(7);
>     atest.machmal(-7);
>
>   }
>
> Sorry .. if I'm too stupid ..
> but I don"t know why
> both cases are so different .. ?
>
> Where is this behaviour documented ?
>
> Thanks a lot !
>
>         Frank
>
>
>
>
>
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