Java - calculate difference between two Dates in days

1. Overview

In java we can calculate difference between two Dates with TimeUnit class.

2. Example of how to calculate difference between two Dates in days

import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.util.Date;
import java.util.concurrent.TimeUnit;

public class CalculateDifferenceBetweenDays {

    public static void main(String[] args) {

        LocalDateTime of1 = LocalDateTime.of(2019, 10,  3, 16, 20, 0, 0);
        LocalDateTime of2 = LocalDateTime.of(2019, 10, 12, 16, 20, 0, 0);

        Date from = Date.from(of1.toInstant(ZoneOffset.UTC));
        Date now  = Date.from(of2.toInstant(ZoneOffset.UTC));

        long differenceDays = calculateDifferenceBetweenTwoDatesInDays(from, now);

        System.out.println("Diff in days: ");
        System.out.println(differenceDays); // 9
    }

    public static long calculateDifferenceBetweenTwoDatesInDays(Date from, Date now) {
        long millisecondsDiff = now.getTime() - from.getTime();
        return TimeUnit.DAYS.convert(millisecondsDiff, TimeUnit.MILLISECONDS);
    }
}

Output:

Diff in days:
9

References

1. LocalDateTime - JavaDoc
2. Date - JavaDoc
3. TimeUnit - JavaDoc
4. ZoneOffset - JavaDoc