Exception handling in Files.walk and Files.find

[Peter Levart]

Hi,

Recently I wanted to use Files.walk method returning a Stream<Path> to 
scan a directory of files. I quickly learned that it is of limited use. 
For example, the following code:

         long pngFilesCount = Files.walk(Paths.get("/usr"))
                 .filter(path -> path.toString().endsWith(".png"))
                 .count();

Throws exception on my computer:

Exception in thread "main" java.io.UncheckedIOException: 
java.nio.file.AccessDeniedException: /usr/share/polkit-1/rules.d

This is a consequence of the fact that some files and/or directories in 
the tree being scanned are not accessible to my user account on the 
computer. If I wanted to skip those files/directories I would be forced 
to use different API (Files.walkFileTree using FileVisitor which can 
handle exceptions too).

I propose the addition of overloads to Files.walk and Files.find that 
take an additional parameter of type Consumer<IOException> to be 
responsible for handling IOExceptions that are thrown while walking the 
file tree:

http://cr.openjdk.java.net/~plevart/jdk9-dev/Files.walkIOException/webrev.01/

Ignoring AccessDeniedException(s) in above code can therefore be coded as:

         long pngFilesCount = Files.walk(Paths.get("/usr"), 
Integer.MAX_VALUE,
                 ioe -> {
                     if (!(ioe instanceof AccessDeniedException)) {
                         throw new UncheckedIOException(ioe);
                     }
                 })
                 .filter(path -> path.toString().endsWith(".png"))
                 .count();

What do you think?

Regards, Peter