FileUtils { public static int getAmountOfFiles(File directory) { return directory.isDirectory() ? Objects.requireNonNull(directory.listFiles()).length : 0; } private  FileUtils(); static boolean contains(File[] files, String fileName); static int getAmountOfFiles(File directory); static String getContentOfFile(File file); static String[] getContentAsLines(File file); static Collection<File> findFilesByExtension(String directory, String extension); static Collection<File> findFilesByExtension(File directory, String extension); static Node<File> collectFiles(File directory); static void overrideFile(File file, String content); static boolean delete(File file); static File[] toFiles(String... paths); static String getName(File file); static String getName(URL url); static String getName(String path);  }
@Test void getAmountOfFiles() { Assertions.assertEquals(4, FileUtils.getAmountOfFiles(directory)); }