How to calculate difference between two dates in years...etc with Joda-Time

Question

import java.text.SimpleDateFormat;
import java.util.Date;
import org.joda.time.*;

public class Test {

  public static void main(String[] args) {

String dateStart = "01/01/2000 05:30";
String dateStop = "02/2/2001 06:31";

SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm");

Date d1 = null;
Date d2 = null;

try {
    d1 = format.parse(dateStart);
    d2 = format.parse(dateStop);

    DateTime dt1 = new DateTime(d1);
    DateTime dt2 = new DateTime(d2);

    System.out.print(Years.yearsBetween(dt1, dt2).getYears() + " years, ");
    System.out.print(Months.monthsBetween(dt1, dt2).getMonths() % 52 + " months, ");
    System.out.print(Weeks.weeksBetween(dt1, dt2).getWeeks() % 4 + " weeks, ");
    System.out.print(Days.daysBetween(dt1, dt2).getDays() % 7 + " days, ");
    System.out.print(Hours.hoursBetween(dt1, dt2).getHours() % 24 + " hours, ");
    System.out.print(Minutes.minutesBetween(dt1, dt2).getMinutes() % 60 + " minutes, ");


 } catch (Exception e) {
    e.printStackTrace();
 }

}

}

I want to output the number of years, months, weeks, days, hours, and minutes between two dates using Joda-Time. My question is where do I implement the number of weeks in a month (which in never constant). I don't think my %'s are right either.

When run I get:

1 years, 13 months, 0 weeks, 6 days, 1 hours, 1 minutes, 

Solution

Period gives you this out of the box.

Period period = new Period(d1, d2);
System.out.print(period.getYears() + " years, ");
System.out.print(period.getMonths() + " months, ");
// ...

To prettify and get a little more control over the output, you can use a PeriodFormatterBuilder.

Comments

[Rob Hruska]

If you just use a Period, will that give you what you're after?

[MrAwesome8]

What do you mean by a Period? I know there are durations, intervals and periods but I do not know the difference.

[Rob Hruska]

stackoverflow.com/questions/2653567/…

[Dawood ibn Kareem]

What do you mean "number of days"? You need to define how you want to treat the 23-hour and 25-hour days that result when daylight savings begins and ends.

[MrAwesome8]

Once minutes exceeds 60 then 1 is added to hours. once hours exceeds 24 then 1 is added to days. once days exceeds 24 then one is added to weeks. etc.

[Rob Hruska]

@DavidWallace Note that Period does account for that: "...periods represent an abstracted definition of a time period (eg. a day may not actually be 24 hours, it might be 23 or 25 at daylight savings boundary)..."

[Dawood ibn Kareem]

Yes, @RobHruska, you are right about that. However, judging from OP's previous comment, that's not actually what he/she wants. Either that, or he/she hasn't thought about it too much.

[Rob Hruska]

@DavidWallace True. Periods are probably what the OP wants - if not, a Duration might be appropriate. If neither, then I have no idea, and pity the person implementing their own date subtraction logic. :)

[Dawood ibn Kareem]

Yes. It's always worth stopping and thinking about these things, just to be sure that you are getting what you think you're getting, and to appreciate all the reasons why you shouldn't be trying to roll your own date arithmetic library.

[MrAwesome8]

Rob was correct. What I needed was a Period.

[Basil Bourque]

FYI, Joda-Time provides a trio of classes defining a span of time: Interva, Period, and Duration. Each has a different angle, and they interoperate with each other. I suggest becoming familiar with all three.

[MrAwesome8]

Thank you, you have been very helpful.

[TheRealChx101]

What is supposed to be d1 and d2?

[Rob Hruska]

@chx101 They're Dates, check out the code in the question for context.

[vphilipnyc]

Actually, they are org.joda.time.DateTime instances (or more specifically, implementations of ReadableInstant)