java file sorting using date or time

1public class ExampleSortFilesByDate {
2  public static void main(String[] args) {
3      File dir = new File("d:\\test");
4      File[] files = dir.listFiles();
5      System.out.println("-- printing files before sort --");
6      printFiles(files);
7      sortFilesByDateCreated(files);
8      System.out.println("-- printing files after sort --");
9      printFiles(files);
10  }
11
12  private static void printFiles(File[] files) {
13      for (File file : files) {
14          long m = getFileCreationEpoch(file);
15          Instant instant = Instant.ofEpochMilli(m);
16          LocalDateTime date = instant.atZone(ZoneId.systemDefault()).toLocalDateTime();
17          System.out.println(date+" - "+file.getName());
18      }
19  }
20
21  public static void sortFilesByDateCreated (File[] files) {
22      Arrays.sort(files, new Comparator<File>() {
23          public int compare (File f1, File f2) {
24              long l1 = getFileCreationEpoch(f1);
25              long l2 = getFileCreationEpoch(f2);
26              return Long.valueOf(l1).compareTo(l2);
27          }
28      });
29  }
30
31  public static long getFileCreationEpoch (File file) {
32      try {
33          BasicFileAttributes attr = Files.readAttributes(file.toPath(),
34                  BasicFileAttributes.class);
35          return attr.creationTime()
36                     .toInstant().toEpochMilli();
37      } catch (IOException e) {
38          throw new RuntimeException(file.getAbsolutePath(), e);
39      }
40  }
41}