Name: rmT116609 Date: 04/22/2003


DESCRIPTION OF THE PROBLEM :
In the Java Tutorial, Trail: Learning the Java Language,
Lesson: "Classes and Inheritance", section: "Implementing
Nested Classes", can be read the following:

"Definition: A nested class is a class that is a member of
another class."

This is not just an error in the definition. The ensuing
discussion continues to equate nested classes with member
classes.

As per the JLS: member classes are those with class-body
scope, i.e., declared directly in the class body, while a
nested class is ANY class defined within another class.
Seems like this topic gives many people trouble, so having
the tutorial get it wrong is probably a bad thing.

In fact, I came upon this bug because I was reading an exam
prep book which has nested-member-inner all jumbled up, and
I wondered if this book's error was being discussed on the
web. My search turned up an impressive assortment of nested
class taxonomies, nearly all of them at odds with the JLS,
including, alas, the Java Tutorial.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1.Enter the current Java Tutorial
2. Pick the trail: Learning the Java Language
3. Pick the lesson: Classes and Inheritance
4. Pick the section: Implementing Nested Classes

http://java.sun.com/docs/books/tutorial/java/javaOO/nested.html



Please see:

http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#44365

The second paragraph states:

/*
A nested class is any class whose declaration occurs within the body of
another class or interface. A top level class is a class that is not a
nested class.
*/

The sixth paragraph is also germain, but I would skip to section 8.5:
http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#2460
26

The first paragraph:

/*
A member class is a class whose declaration is directly enclosed in another
class or interface declaration. Similarly, a member interface is an
interface whose declaration is directly enclosed in another class or
interface declaration. The scope (?6.3) of a member class or interface is
specified in ?8.1.5.
*/

The crucial phrase is "directly enclosed". This is about scope. The two
sections mentioned in the above paragraph lay this out:

Section 8.1.5:
http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#1898
8

The line after the grammar is:

/*
The scope of a declaration of a member m declared in or inherited by a class
type C is the entire body of C, including any nested type declarations.
*/

I would keep reading right into section 8.2, in particular:

/*
The members of a class type are all of the following:

Members inherited from its direct superclass (?8.1.3), except in class
Object, which has no direct superclass
Members inherited from any direct superinterfaces (?8.1.4)
Members declared in the body of the class (?8.1.5)
*/

Section 6.3 is mentioned only to further nail down the scope of a member
declaration - it is the source of 8.1.5's definition of member scope:
http://java.sun.com/docs/books/jls/second_edition/html/names.doc.html#103228

Boiling all this down into simple statements (hopefully an improvement over
my previous attempt):

The members of a class are those fields, methods, classes, and interfaces
which have member scope. Member scope means visibility throughout the body
of the class. A member class therefore is declared directly in the body of
its enclosing class (not within an expression or block of any kind).
Anonymous and local classes are not members.


REPRODUCIBILITY :
This bug can be reproduced always.
(Review ID: 180561)
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