Recursive stream

Question

I want to list all the files on my computer recursively using Java 8.

Java 8 provides a listFiles method that returns all the files and directories but

Answer 1

A new API to generate a stream of Paths by walking the filesystem recursively is Files.walk.

If you really want to generate a stream recursively (not necessarily walking the file tree, but I'll continue using that as an example), it might be a bit more straightforward to accomplish the recursion using method references:

class RecursiveStream {
    static Stream listFiles(Path path) {
        if (Files.isDirectory(path)) {
            try { return Files.list(path).flatMap(RecursiveStream::listFiles); }
            catch (Exception e) { return Stream.empty(); }
        } else {
            return Stream.of(path);
        }
    }

    public static void main(String[] args) {
        listFiles(Paths.get(".")).forEach(System.out::println);
    }
}

Method references turn out to be quite useful for adapting a named method that has the same "shape" (arguments and return type) as a functional interface to that functional interface. This also avoids the potential initialization circularity with storing a lambda in an instance or static variable and calling itself recursively.