A DESCRIPTION OF THE REQUEST :
See question on SO:

http://stackoverflow.com/questions/22867286/files-walk-calculate-total-size

When walking over some files using Files.walk(), some files can't be visited
and we will get an exception:
Exception in thread "main" java.io.UncheckedIOException: java.nio.file.AccessDeniedException: c:\$Recycle.Bin\S-1-5-20
at java.nio.file.FileTreeIterator.fetchNextIfNeeded(Unknown Source)
at java.nio.file.FileTreeIterator.hasNext(Unknown Source)


JUSTIFICATION :
Comment from SO:
"I believe this is a design failure, because as it stands now Files.walk is absolutely unusable, because you never can guarantee that there will be no errors when walking over a directory."

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
One proposal from SO:

1. "I believe it can still be fixed, though I do not know how FileVisitOptions exactly work.
Currently there is a FileVisitOption.FOLLOW_LINKS, if it operates on a per file basis, then I would suspect that a FileVisitOption.IGNORE_ON_IOEXCEPTION could also be added, however we cannot correctly inject that functionality in there."

and my own:
2: I think i would prefer maybe another Files.walk() that also accepted an errorHandler or similiar.

---------- BEGIN SOURCE ----------
public static void main(String[] args) throws IOException {
    long size = Files.walk(Paths.get("c:/")).mapToLong(MyMain::count).sum();
    System.out.println("size=" + size);
}

static long count(Path path) {
    try {
        return Files.size(path);
    } catch (IOException | UncheckedIOException e) {
        return 0;
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Use the old java-7 Files.walkFileTree api and implement an anonymous visitor class.