How to calculate "time ago" in Java?

Question

In Ruby on Rails, there is a feature that allows you to take any Date and print out how "long ago" it was.

For example:

8 minutes ago
8 hours ago
8 days ago
8 months ago
8 years ago

Is there an easy way to do this in Java?

Answer 1

Take a look at the PrettyTime library.

Answer 2

The joda-time package, has the notion of Periods. You can do arithmetic with Periods and DateTimes.

From the docs:

public boolean isRentalOverdue(DateTime datetimeRented) {
  Period rentalPeriod = new  Period().withDays(2).withHours(12);
  return datetimeRented.plus(rentalPeriod).isBeforeNow();
}

Answer 3

It's not pretty...but the closest I can think of is using Joda-Time (as described in this post: How to calculate elapsed time from now with Joda Time?

Answer 4

You can achieve this using Calendar in Java.

calendar1.set(2007, 01, 10);
calendar2.set(2007, 07, 01); //ADD Current date with time here (see set(..) in Calendar)

    long milliseconds1 = calendar1.getTimeInMillis();
    long milliseconds2 = calendar2.getTimeInMillis();
    long diff = milliseconds2 - milliseconds1;
    long diffSeconds = diff / 1000;

    System.out.println("Time in milliseconds: " + diff + " milliseconds.");

Output: Time in milliseconds: 14860800000 milliseconds.

Source

http://download.oracle.com/javase/1.4.2/docs/api/java/util/Calendar.html#set%28int,%20int,%20int,%20int,%20int%29

Answer 5

Have you considered the TimeUnit enum? It can be pretty useful for this kind of thing

    SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy");
    Date past = format.parse("01/10/2010");
    Date now = new Date();

    System.out.println(TimeUnit.MILLISECONDS.toMillis(now.getTime() - past.getTime()) + " milliseconds ago");
    System.out.println(TimeUnit.MILLISECONDS.toMinutes(now.getTime() - past.getTime()) + " minutes ago");
    System.out.println(TimeUnit.MILLISECONDS.toHours(now.getTime() - past.getTime()) + " hours ago");
    System.out.println(TimeUnit.MILLISECONDS.toDays(now.getTime() - past.getTime()) + " days ago");

Answer 6

  public class TimeUtils {

      public final static long ONE_SECOND = 1000;
      public final static long SECONDS = 60;

      public final static long ONE_MINUTE = ONE_SECOND * 60;
      public final static long MINUTES = 60;

      public final static long ONE_HOUR = ONE_MINUTE * 60;
      public final static long HOURS = 24;

      public final static long ONE_DAY = ONE_HOUR * 24;

      private TimeUtils() {
      }

      /**
       * converts time (in milliseconds) to human-readable format
       *  "<w> days, <x> hours, <y> minutes and (z) seconds"
       */
      public static String millisToLongDHMS(long duration) {
        StringBuffer res = new StringBuffer();
        long temp = 0;
        if (duration >= ONE_SECOND) {
          temp = duration / ONE_DAY;
          if (temp > 0) {
            duration -= temp * ONE_DAY;
            res.append(temp).append(" day").append(temp > 1 ? "s" : "")
               .append(duration >= ONE_MINUTE ? ", " : "");
          }

          temp = duration / ONE_HOUR;
          if (temp > 0) {
            duration -= temp * ONE_HOUR;
            res.append(temp).append(" hour").append(temp > 1 ? "s" : "")
               .append(duration >= ONE_MINUTE ? ", " : "");
          }

          temp = duration / ONE_MINUTE;
          if (temp > 0) {
            duration -= temp * ONE_MINUTE;
            res.append(temp).append(" minute").append(temp > 1 ? "s" : "");
          }

          if (!res.toString().equals("") && duration >= ONE_SECOND) {
            res.append(" and ");
          }

          temp = duration / ONE_SECOND;
          if (temp > 0) {
            res.append(temp).append(" second").append(temp > 1 ? "s" : "");
          }
          return res.toString();
        } else {
          return "0 second";
        }
      }


      public static void main(String args[]) {
        System.out.println(millisToLongDHMS(123));
        System.out.println(millisToLongDHMS((5 * ONE_SECOND) + 123));
        System.out.println(millisToLongDHMS(ONE_DAY + ONE_HOUR));
        System.out.println(millisToLongDHMS(ONE_DAY + 2 * ONE_SECOND));
        System.out.println(millisToLongDHMS(ONE_DAY + ONE_HOUR + (2 * ONE_MINUTE)));
        System.out.println(millisToLongDHMS((4 * ONE_DAY) + (3 * ONE_HOUR)
            + (2 * ONE_MINUTE) + ONE_SECOND));
        System.out.println(millisToLongDHMS((5 * ONE_DAY) + (4 * ONE_HOUR)
            + ONE_MINUTE + (23 * ONE_SECOND) + 123));
        System.out.println(millisToLongDHMS(42 * ONE_DAY));
        /*
          output :
                0 second
                5 seconds
                1 day, 1 hour
                1 day and 2 seconds
                1 day, 1 hour, 2 minutes
                4 days, 3 hours, 2 minutes and 1 second
                5 days, 4 hours, 1 minute and 23 seconds
                42 days
         */
    }
}

more @Format a duration in milliseconds into a human-readable format