Get the number of days, weeks, and months, since Epoch in Java

java time calendar epoch
Ariel Vardi picture Ariel Vardi · May 27, 2011 · Viewed 41.2k times · Source

I'm trying to get the number of days, weeks, months since Epoch in Java.

The Java Calendar class offers things like calendar.get(GregorianCalendar.DAY_OF_YEAR), or Calendar.get(GregorianCalendar.WEEK_OF_YEAR), which is a good start but it doesn't do exactly what I need.

Is there an elegant way to do this in Java?

Answer

bamana picture bamana · May 28, 2011

You can use the Joda Time library to do this pretty easily - I use it for anything time related other than using the standard Java Date and Calendar classes. Take a look at the example below using the library:

MutableDateTime epoch = new MutableDateTime();
epoch.setDate(0); //Set to Epoch time
DateTime now = new DateTime();

Days days = Days.daysBetween(epoch, now);
Weeks weeks = Weeks.weeksBetween(epoch, now);
Months months = Months.monthsBetween(epoch, now);

System.out.println("Days Since Epoch: " + days.getDays());
System.out.println("Weeks Since Epoch: " + weeks.getWeeks());
System.out.println("Months Since Epoch: " + months.getMonths());

When I run this I get the following output:

Days Since Epoch: 15122
Weeks Since Epoch: 2160
Months Since Epoch: 496

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