I have 2 dates:

LocalDate date1 = LocalDate.now().minusDays(40);
LocalDate date2 = LocalDate.now();

I want to figure out what is the biggest time unit I can pick to define the difference between the 2 (out of days, months, years), and to get its number. The perfect solution for me, I think, would been if Duration of java.time api had also toMonthsPart and toYearsPart as it has toDaysPart. This way I could do this:

Duration dif = Duration.between(date1, date2);

long daysPart = dif.toDaysPart();
if (daysPart > 0) {
    return ChronoUnit.DAYS.between(date1, date2);
}

long monthPart = dif.getMonthsPart();
if (monthPart > 0) {
    return ChronoUnit.MONTHS.between(date1, date2);
}

long yearPart = dif.getYearsPart();
if (yearPart > 0) {
    return ChronoUnit.YEARS.between(date1, date2);
}

throw new Exception("no difference");

But there is no such methods in the API. Is there another package can provide this functionality, or do you know of different approach to achieve my goal?

CodePudding user response：

TL;DR

Use Period instead of Duration.

Demo:

import java.time.LocalDate;
import java.time.Period;

class Main {
    public static void main(String[] args) {
        LocalDate today = LocalDate.now();
        LocalDate fortyDaysAgo = today.minusDays(40);
        Period period = Period.between(fortyDaysAgo, today);
        System.out.println(period);
        System.out.printf("%d year(s) %d month(s) %d day(s)%n", period.getYears(), period.getMonths(),
                period.getDays());
    }
}

Output from a sample run:

P1M9D
0 year(s) 1 month(s) 9 day(s)

ONLINE DEMO

Learn more about the modern Date-Time API from Trail: Date Time.