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

From:
Tom Anderson <twic@urchin.earth.li>
Newsgroups:
comp.lang.java.help
Date:
Sun, 13 Sep 2009 14:43:31 +0100
Message-ID:
<alpine.DEB.1.10.0909131430500.26614@urchin.earth.li>
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:

56d17h23m56s

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);
System.out.println(timeStr);
}
}
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
ingenuity.

tom

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