How to Calculate Elapsed Time from Now with Joda-Time

How to calculate elapsed time from now with Joda-Time?

To calculate the elapsed time with JodaTime, use Period. To format the elapsed time in the desired human representation, use PeriodFormatter which you can build by PeriodFormatterBuilder.

Here's a kickoff example:

DateTime myBirthDate = new DateTime(1978, 3, 26, 12, 35, 0, 0);
DateTime now = new DateTime();
Period period = new Period(myBirthDate, now);

PeriodFormatter formatter = new PeriodFormatterBuilder()
    .appendSeconds().appendSuffix(" seconds ago\n")
    .appendMinutes().appendSuffix(" minutes ago\n")
    .appendHours().appendSuffix(" hours ago\n")
    .appendDays().appendSuffix(" days ago\n")
    .appendWeeks().appendSuffix(" weeks ago\n")
    .appendMonths().appendSuffix(" months ago\n")
    .appendYears().appendSuffix(" years ago\n")
    .printZeroNever()
    .toFormatter();

String elapsed = formatter.print(period);
System.out.println(elapsed);

This prints by now

3 seconds ago
51 minutes ago
7 hours ago
6 days ago
10 months ago
31 years ago

^{_{(Cough, old, cough)}} You see that I've taken months and years into account as well and configured it to omit the values when those are zero.

Joda Time: Calculate time to next full interval in month

Note: Check the following notice at the Home Page of Joda-Time

Joda-Time is the de facto standard date and time library for Java
prior to Java SE 8. Users are now asked to migrate to java.time
(JSR-310).

Therefore, I recommend you do it with the java.time API using the following methods:

1. LocalDateTime#isBefore
2. LocalDateTime#plusWeeks
3. LocalDateTime#plusMonths

Using the java.time API:

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        LocalDateTime creation = createLocalDateTime("01.01.2021 06:30:00");
        LocalDateTime due = createLocalDateTime("12.01.2021 05:30:00");
        System.out.println(getNextWeeklyIntervalDate(creation, due, 1));
        System.out.println(getNextMonthlyIntervalDate(creation, due, 1));
    }

    static LocalDateTime getNextWeeklyIntervalDate(LocalDateTime creationTime, LocalDateTime dueTime,
            int intervalInWeeks) {
        LocalDateTime ldt = creationTime;
        while (ldt.isBefore(dueTime)) {
            ldt = ldt.plusWeeks(intervalInWeeks);
        }
        return ldt;
    }

    static LocalDateTime getNextMonthlyIntervalDate(LocalDateTime creationTime, LocalDateTime dueTime,
            int intervalInMonth) {
        LocalDateTime ldt = creationTime;
        while (ldt.isBefore(dueTime)) {
            ldt = ldt.plusMonths(intervalInMonth);
        }
        return ldt;
    }

    static LocalDateTime createLocalDateTime(String dateTimeStr) {
        return LocalDateTime.parse(dateTimeStr, DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm:ss", Locale.ENGLISH));
    }
}

Output:

2021-01-15T06:30
2021-02-01T06:30

These methods are available in Joda-time API as well i.e. all you need to change is the way how the date-time string is parsed and LocalDateTime is obtained.

Using Joda-time API:

import org.joda.time.LocalDateTime;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        LocalDateTime creation = createLocalDateTime("01.01.2021 06:30:00");
        LocalDateTime due = createLocalDateTime("12.01.2021 05:30:00");
        System.out.println(getNextWeeklyIntervalDate(creation, due, 1));
        System.out.println(getNextMonthlyIntervalDate(creation, due, 1));
    }

    static LocalDateTime getNextWeeklyIntervalDate(LocalDateTime creationTime, LocalDateTime dueTime,
            int intervalInWeeks) {
        LocalDateTime ldt = creationTime;
        while (ldt.isBefore(dueTime)) {
            ldt = ldt.plusWeeks(intervalInWeeks);
        }
        return ldt;
    }

    static LocalDateTime getNextMonthlyIntervalDate(LocalDateTime creationTime, LocalDateTime dueTime,
            int intervalInMonth) {
        LocalDateTime ldt = creationTime;
        while (ldt.isBefore(dueTime)) {
            ldt = ldt.plusMonths(intervalInMonth);
        }
        return ldt;
    }

    static LocalDateTime createLocalDateTime(String dateTimeStr) {
        DateTimeFormatter dtf = DateTimeFormat.forPattern("dd.MM.yyyy HH:mm:ss");
        LocalDateTime ldt = dtf.parseDateTime(dateTimeStr).toLocalDateTime();
        return ldt;
    }
}

Output:

2021-01-15T06:30:00.000
2021-02-01T06:30:00.000

As you can see, every thing, except the code inside createLocalDateTime, is same for both java.time and Joda-time API.

How do I measure time elapsed in Java?

Unfortunately, none of the ten answers posted so far are quite right.

If you are measuring elapsed time, and you want it to be correct, you must use System.nanoTime(). You cannot use System.currentTimeMillis(), unless you don't mind your result being wrong.

The purpose of nanoTime is to measure elapsed time, and the purpose of currentTimeMillis is to measure wall-clock time. You can't use the one for the other purpose. The reason is that no computer's clock is perfect; it always drifts and occasionally needs to be corrected. This correction might either happen manually, or in the case of most machines, there's a process that runs and continually issues small corrections to the system clock ("wall clock"). These tend to happen often. Another such correction happens whenever there is a leap second.

Since nanoTime's purpose is to measure elapsed time, it is unaffected by any of these small corrections. It is what you want to use. Any timings currently underway with currentTimeMillis will be off -- possibly even negative.

You may say, "this doesn't sound like it would ever really matter that much," to which I say, maybe not, but overall, isn't correct code just better than incorrect code? Besides, nanoTime is shorter to type anyway.

Previously posted disclaimers about nanoTime usually having only microsecond precision are valid. Also it can take more than a whole microsecond to invoke, depending on circumstances (as can the other one), so don't expect to time very very small intervals correctly.

Number of days between two dates in Joda-Time

Annoyingly, the withTimeAtStartOfDay answer is wrong, but only occasionally. You want:

Days.daysBetween(start.toLocalDate(), end.toLocalDate()).getDays()

It turns out that "midnight/start of day" sometimes means 1am (daylight savings happen this way in some places), which Days.daysBetween doesn't handle properly.

// 5am on the 20th to 1pm on the 21st, October 2013, Brazil
DateTimeZone BRAZIL = DateTimeZone.forID("America/Sao_Paulo");
DateTime start = new DateTime(2013, 10, 20, 5, 0, 0, BRAZIL);
DateTime end = new DateTime(2013, 10, 21, 13, 0, 0, BRAZIL);
System.out.println(daysBetween(start.withTimeAtStartOfDay(),
                               end.withTimeAtStartOfDay()).getDays());
// prints 0
System.out.println(daysBetween(start.toLocalDate(),
                               end.toLocalDate()).getDays());
// prints 1

Going via a LocalDate sidesteps the whole issue.

Calculating the difference between two Java date instances

The JDK Date API is horribly broken unfortunately. I recommend using Joda Time library.

Joda Time has a concept of time Interval:

Interval interval = new Interval(oldTime, new Instant());

EDIT: By the way, Joda has two concepts: Interval for representing an interval of time between two time instants (represent time between 8am and 10am), and a Duration that represents a length of time without the actual time boundaries (e.g. represent two hours!)

If you only care about time comparisions, most Date implementations (including the JDK one) implements Comparable interface which allows you to use the Comparable.compareTo()

How to find n'th previous Sunday with Java date time API or Joda-time?

You basically need to check if today is Sunday, if not, then look back for the previous one...(or recursively move back the date if you need the previous one to that...)

Using java 8 you will need:

• DayOfWeek enumerator

• TemporalAdjusters#previous

---

LocalDate date = LocalDate.now();
DayOfWeek todayAsDayOfWeek = date.getDayOfWeek();
LocalDate prevSun = todayAsDayOfWeek == DayOfWeek.SUNDAY ? date : date.with(TemporalAdjusters.previous(DayOfWeek.SUNDAY));
System.out.println(prevSun);

---

Edit: previousOrSame method will skip the check of the actual dayof the week

    LocalDate date = LocalDate.now();
    LocalDate prevSun = date.with(TemporalAdjusters.previous(DayOfWeek.SUNDAY));

    prevSun = date.with(TemporalAdjusters.previousOrSame(DayOfWeek.SUNDAY));
    System.out.println(prevSun);

How can I calculate a time difference in Java?

String time1 = "16:00:00";
String time2 = "19:00:00";

SimpleDateFormat format = new SimpleDateFormat("HH:mm:ss");
Date date1 = format.parse(time1);
Date date2 = format.parse(time2);
long difference = date2.getTime() - date1.getTime(); 

Difference is in milliseconds.

I modified sfaizs post.

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