public static void main(String[] args) {
    try (BufferedReader reader = Files.newBufferedReader(
            Paths.get("myfile.txt"),
            StandardCharsets.UTF_8)) {
        System.out.println(reader.lines().count());
    } catch (IOException ex) {
    }
}

         int arr[] = new int[13];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = i;
        }
        
    // реверсия массива 
        for (int i = 0; i < arr.length/2; i++) {
            int j = arr[i];
            arr[i] =arr[arr.length - 1 - i] ;
            arr[arr.length - 1 - i] = j;
            
        }
        
// вывод массива в виде строки 
        System.out.println(Arrays.toString(arr));

public static void main(String[] args) {
    try (BufferedReader reader = Files.newBufferedReader(
            Paths.get("myfile.txt"),
            StandardCharsets.UTF_8)) {
        reader.lines().forEach(System.out::println);
    } catch (IOException ex) {
    }
}

button.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent ae) {
      System.out.println(“Action Detected”);
    }
  }
);

button.addActionListener(e -> {
        System.out.println(“Action Detected”);
    }
);