Re: How to convert x (elapsed) milliseconds into human-readable format "..d..h..m..s" ?

Tom Anderson <>
Sun, 13 Sep 2009 14:43:31 +0100
On Sun, 13 Sep 2009, Ulf Meinhardt wrote:

Assume I have a number of milliseconds.

How can I convert this value into a more human-readable format
with days, hours, minutes and seconds like:


If the number of days is equals to 0 then the "d" part should be omitted.

I don't think there's anything in the standard library that will do this -
my gut feeling is that you can't twist Calendar into doing this, but i
could very well be wrong.

Here's how i'd do it, with a nice fallthrough switch statement:

public class UlfTime {
  public static void main(String... args) {
  for (String arg: args) {
  long time = Long.parseLong(arg);
  String timeStr = format(time);
  private static enum TimeUnit {MILLISECONDS, SECONDS, MINUTES, HOURS, DAYS}
  public static String format(long time) {
  if (time < 0L) throw new IllegalArgumentException("negative time: " + time);
  TimeUnit largest;
  int ms = (int)(time % 1000);
  largest = TimeUnit.MILLISECONDS;
  time /= 1000;
  int s = (int)(time % 60);
  if (s != 0) largest = TimeUnit.SECONDS;
  time /= 60;
  int m = (int)(time % 60);
  if (m != 0) largest = TimeUnit.MINUTES;
  time /= 60;
  int h = (int)(time % 24);
  if (h != 0) largest = TimeUnit.HOURS;
  time /= 24;
  long d = time;
  if (d != 0) largest = TimeUnit.DAYS;
  StringBuilder sb = new StringBuilder();
  switch (largest) {
  case DAYS: sb.append(d); sb.append("d");
  case HOURS: sb.append(h); sb.append("h");
  case MINUTES: sb.append(m); sb.append("m");
  case SECONDS: sb.append(s); sb.append("s");
  case MILLISECONDS: sb.append(ms); sb.append("ms");
  return sb.toString();

This could almost certainly be expressed more compactly with a little


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