我认为最好的办法是:

String.format("%d min, %d sec", 
    TimeUnit.MILLISECONDS.toSeconds(length)/60,
    TimeUnit.MILLISECONDS.toSeconds(length) % 60 );

    long startTime = System.currentTimeMillis();
    // do your work...
    long endTime=System.currentTimeMillis();
    long diff=endTime-startTime;       
    long hours=TimeUnit.MILLISECONDS.toHours(diff);
    diff=diff-(hours*60*60*1000);
    long min=TimeUnit.MILLISECONDS.toMinutes(diff);
    diff=diff-(min*60*1000);
    long seconds=TimeUnit.MILLISECONDS.toSeconds(diff);
    //hour, min and seconds variables contains the time elapsed on your work

有个问题。当毫秒为59999时，实际上是1分钟，但它将被计算为59秒，损失了999毫秒。

以下是根据之前的答案修改后的版本，可以解决这个损失:

public static String formatTime(long millis) {
    long seconds = Math.round((double) millis / 1000);
    long hours = TimeUnit.SECONDS.toHours(seconds);
    if (hours > 0)
        seconds -= TimeUnit.HOURS.toSeconds(hours);
    long minutes = seconds > 0 ? TimeUnit.SECONDS.toMinutes(seconds) : 0;
    if (minutes > 0)
        seconds -= TimeUnit.MINUTES.toSeconds(minutes);
    return hours > 0 ? String.format("%02d:%02d:%02d", hours, minutes, seconds) : String.format("%02d:%02d", minutes, seconds);
}

DurationFormatUtils.formatDurationHMS(长)

回顾@brent-nash的贡献，我们可以使用模函数代替减法并使用String。结果字符串的格式方法:

  /**
   * Convert a millisecond duration to a string format
   * 
   * @param millis A duration to convert to a string form
   * @return A string of the form "X Days Y Hours Z Minutes A Seconds B Milliseconds".
   */
   public static String getDurationBreakdown(long millis) {
       if (millis < 0) {
          throw new IllegalArgumentException("Duration must be greater than zero!");
       }

       long days = TimeUnit.MILLISECONDS.toDays(millis);
       long hours = TimeUnit.MILLISECONDS.toHours(millis) % 24;
       long minutes = TimeUnit.MILLISECONDS.toMinutes(millis) % 60;
       long seconds = TimeUnit.MILLISECONDS.toSeconds(millis) % 60;
       long milliseconds = millis % 1000;

       return String.format("%d Days %d Hours %d Minutes %d Seconds %d Milliseconds",
                            days, hours, minutes, seconds, milliseconds);
   }

首先，System.currentTimeMillis()和Instant.now()对于计时来说并不理想。它们都报告了挂钟时间，而计算机并不能准确地知道这个时间，而且它可能会不规律地移动，例如，如果NTP守护进程更正了系统时间，就会往回走。如果计时发生在一台机器上，那么应该使用System.nanoTime()。

其次，从Java 8开始，Java .time. duration是表示持续时间的最佳方式:

long start = System.nanoTime();
// do things...
long end = System.nanoTime();
Duration duration = Duration.ofNanos(end - start);
System.out.println(duration); // Prints "PT18M19.511627776S"
System.out.printf("%d Hours %d Minutes %d Seconds%n",
        duration.toHours(), duration.toMinutes() % 60, duration.getSeconds() % 60);
// prints "0 Hours 18 Minutes 19 Seconds"