Sybex 829 - Errata - page 847 - Table 14.13

[Daniel Odrinski]

Hi there,
Whilst reading the study guide, specifically page 847 in Chapter 14, I noticed that the example given in Table 14.13 appears to be correct all the way up to the last line.

The next-to-last line reads as follows:

Depth	Path reached
3	/birds/robin/allBirds/robin/pictures
	-> /birds/robin/pictures

This makes sense since 'allBirds' is a symlink/symbolic link to '/birds/'.

However, the next and final line in the table reads:

Depth	Path reached
3	/birds/robin/allBirds/robin/pictures/allBirds
	/birds/robin/allBirds
	-> /birds

(Bold emphasis added by me).

The issue I see is that 'allBirds' appears to be a child of 'pictures' at this point?
I think that this may be a confusion which occurred since the next-to-last line is '/birds/robin/allBirds/robin/pictures', so it may have just been copied and '/allBirds' appended to this line.

I put together a small demo to verify this with a directory structure as follows:

birds
└───robin
    ├───pictures
    └───xallBirds -> ..\..\ i.e. birds

using the PowerShell command:

<project root>\birds\robin> New-Item -ItemType SymbolicLink -Path .\xallBirds -Target  ..\

where '->' is a symlink and which when traversed using Windows' 'tree' command, results in the following output:

birds
└───robin
    ├───pictures
    └───xallBirds
        └───robin
            ├───pictures
            └───xallBirds
                └───robin
                    ├───pictures
                    └───xallBirds
                        └───robin
                            ... You get the point.

I named the symlink 'xallBirds' instead of 'allBirds' in order to get the code below and the 'tree' command to traverse the 'pictures' directory first (and keep the example simple).

And executed the following code over this directory structure:

        var pathToTraverse = Path.of("birds","robin","xallBirds","robin");
        try (var s = Files.find(pathToTraverse, 10, (p, a) -> a.isDirectory(), FileVisitOption.FOLLOW_LINKS)){
            s.forEach(System.out::println);
        }

Now, I am aware that the example in the book uses a breadth-first search and I am using a method which does a depth-first search. However, the issue here lies in the path given and not in search order.
Notice that I start past the first filesystem cycle  (by setting the 'pathToTraverse' variable on the first line accordingly) to avoid a FileSystemLoopException before I get output similar to (but correct) the last scenario in Table 14.13:

birds\robin\xallBirds\robin
birds\robin\xallBirds\robin\pictures
birds\robin\xallBirds\robin\xallBirds <------- Correct path here [no 'pictures' in path]

Of course, I still get a FileSystemLoopException on the next traversal, but that's besides the point. The output above is of importance.

Is this a legitimate error in the book or am I missing something?

Thank you.

[Jeanne Boyarsky]

You are correct! I've added this to the Java 11 and 17 errata and credited you. (This text wasn't in the Java 8 edition of the book)