I am trying to calculate the difference between two `LocalDateTime`

.

The output needs to be of the format `y years m months d days h hours m minutes s seconds`

. Here is what I have written:

```
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.ZoneId;
public class Main {
static final int MINUTES_PER_HOUR = 60;
static final int SECONDS_PER_MINUTE = 60;
static final int SECONDS_PER_HOUR = SECONDS_PER_MINUTE * MINUTES_PER_HOUR;
public static void main(String[] args) {
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 9, 19, 46, 45);
LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
Period period = getPeriod(fromDateTime, toDateTime);
long time[] = getTime(fromDateTime, toDateTime);
System.out.println(period.getYears() + " years " +
period.getMonths() + " months " +
period.getDays() + " days " +
time[0] + " hours " +
time[1] + " minutes " +
time[2] + " seconds.");
}
private static Period getPeriod(LocalDateTime dob, LocalDateTime now) {
return Period.between(dob.toLocalDate(), now.toLocalDate());
}
private static long[] getTime(LocalDateTime dob, LocalDateTime now) {
LocalDateTime today = LocalDateTime.of(now.getYear(),
now.getMonthValue(), now.getDayOfMonth(), dob.getHour(), dob.getMinute(), dob.getSecond());
Duration duration = Duration.between(today, now);
long seconds = duration.getSeconds();
long hours = seconds / SECONDS_PER_HOUR;
long minutes = ((seconds % SECONDS_PER_HOUR) / SECONDS_PER_MINUTE);
long secs = (seconds % SECONDS_PER_MINUTE);
return new long[]{hours, minutes, secs};
}
}
```

The output that I am getting is `29 years 8 months 24 days 12 hours 0 minutes 50 seconds`

. I have checked my result from this website (with values `12/16/1984 07:45:55`

and `09/09/2014 19:46:45`

). The following screenshot shows the output:

I am pretty sure that the fields after the month value is coming wrong from my code. Any suggestion would be very helpful.

## Update

I have tested my result from another website and the result I got is different. Here it is: Calculate duration between two dates (result: 29 years, 8 months, 24 days, 12 hours, 0 minutes and 50 seconds).

## Update

Since I got two different results from two different sites, I am wondering if the algorithm of my calculation is legitimate or not. If I use following two `LocalDateTime`

objects:

```
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 40, 45);
LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
```

Then the output is coming: `29 years 8 months 25 days -1 hours -5 minutes -10 seconds.`

From this link it should be `29 years 8 months 24 days 22 hours, 54 minutes and 50 seconds`

. So the algorithm needs to handle the negative numbers too.

**Note the question is not about which site gave me what result, I need to know the right algorithm and need to have right results.**

## Best Answer

I found the best way to do this is with

ChronoUnit.Additional documentation is here: https://docs.oracle.com/javase/tutorial/datetime/iso/period.html