Java で 2 つの日付間の期間を効率的に計算するにはどうすればよいですか?

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

class DurationCalculator {

    public static void main(String[] args) {
        // Custom date format
        SimpleDateFormat format = new SimpleDateFormat("yy/MM/dd HH:mm:ss");

        // Sample dates
        String dateStart = "11/03/14 09:29:58";
        String dateStop = "11/03/14 09:33:43";

        Date d1 = null;
        Date d2 = null;
        try {
            d1 = format.parse(dateStart);
            d2 = format.parse(dateStop);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        // Calculate the difference in milliseconds
        long diff = d2.getTime() - d1.getTime();
    }
}

import java.util.Date;
import java.util.concurrent.TimeUnit;

class ImprovedDurationCalculator {

    public static void main(String[] args) {
        Date startDate = // Set start date
        Date endDate = // Set end date

        long duration = endDate.getTime() - startDate.getTime();

        // Calculate the duration in seconds, minutes, hours, and days
        long diffInSeconds = TimeUnit.MILLISECONDS.toSeconds(duration);
        long diffInMinutes = TimeUnit.MILLISECONDS.toMinutes(duration);
        long diffInHours = TimeUnit.MILLISECONDS.toHours(duration);
        long diffInDays = TimeUnit.MILLISECONDS.toDays(duration);
    }
}