Java 8
Path sourcepath = Paths.get("C:\\data\\temp\\mydir");
        Path destinationepath = Paths.get("C:\\data\\temp\\destinationDir");        
        Files.walk(sourcepath)
             .forEach(source -> copy(source, destinationepath.resolve(sourcepath.relativize(source)))); 
Copy Method
static void copy(Path source, Path dest) {
        try {
            Files.copy(source, dest, StandardCopyOption.REPLACE_EXISTING);
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage(), e);
        }
    }