ublic class Walk {

    private final Path filePathIn;
    private final Path filePathOut;

    private static final int SIZE = 1024;
    private static final int INIT = 0x811c9dc5;
    private static final int PRIME = 0x01000193;

    private Walk(final String pathIn, final String pathOut) throws WalkException {
        try {
            filePathIn = Paths.get(pathIn);
        } catch (InvalidPathException error) {
            throw new WalkException("Wrong input file path: " + error.getMessage());
        }
        try {
            filePathOut = Paths.get(pathOut);
        } catch (InvalidPathException error) {
            throw new WalkException("Wrong output file path: " + error.getMessage());
        }
        try {
            if (Files.notExists(filePathOut) && filePathOut.getParent() != null) {
                Files.createDirectory(filePathOut.getParent());
            }
        } catch (IOException error) {
            System.err.println("Can't create directory: " + filePathOut.getParent().toString());
        }
    }

    private static int calculateHash(final Path inPath) {
        try {
            int blockSize;
            int hash = INIT;
            InputStream reader = Files.newInputStream(inPath);
            byte[] bytes = new byte[SIZE];
            while ((blockSize = reader.read(bytes)) >= 0) {
                for (int i = 0; i < blockSize; i++) {
                    hash = (hash * PRIME) ^ (bytes[i] & 0xff);
                }
            }
            return hash;
        } catch (IOException error) {
            return INIT;
        }
    }

    public static void main(String[] args) {
        try {
            if (args != null && args.length == 2 && args[0] != null && args[1] != null) {
                Walk walker = new Walk(args[0], args[1]);
                try (BufferedReader reader = Files.newBufferedReader(walker.filePathIn, StandardCharsets.UTF_8)) {
                    try (BufferedWriter writer = Files.newBufferedWriter(walker.filePathOut, StandardCharsets.UTF_8)) {
                        String filePath;
                        while ((filePath = reader.readLine()) != null) {
                            writer.write(String.format("%08x", calculateHash(Paths.get(filePath))) + ' ' + filePath + '\n');
                        }
                    } catch (FileNotFoundException error) {
                        throw new WalkException("Can't find a file: " + error.getMessage());
                    } catch (IOException error) {
                        throw new WalkException("Something went wrong: " + error.getMessage());
                    }
                } catch (FileNotFoundException error) {
                    throw new WalkException("Can't find a file:: " + error.getMessage());
                } catch (IOException error) {
                    throw new WalkException("Something went wrong: " + error.getMessage());
                }
            } else {
                throw new WalkException("Wrong arguments: \"input file\" \"output file\"");
            }
        } catch (WalkException error) {
            System.err.println(error.getMessage());
        }
    }

}