Java Data Type How to - Calculate elapsed time

Question

We would like to know how to calculate elapsed time.
Answer

import java.util.Calendar;
//from  ww w. j ava  2 s  .  com
public class Main {
    public static void main(String[] args) throws Exception {
        Calendar start = Calendar.getInstance();
        start.set(2015, 1, 21, 11, 1, 11); 
        Calendar end = Calendar.getInstance();

        
        Calendar clone = (Calendar) start.clone();
        int year = elapsed(clone, end, Calendar.YEAR);
        System.out.println(year+" year");
        clone.add(Calendar.YEAR, year);
        int month = elapsed(clone, end, Calendar.MONTH);
        clone.add(Calendar.MONTH, month);
        System.out.println(month+" month");
        
        int date = elapsed(clone, end, Calendar.DATE);
        clone.add(Calendar.DATE, date);
        System.out.println(date+" day");
        
        int hour = (int) (end.getTimeInMillis() - clone.getTimeInMillis()) / 3600000;
        clone.add(Calendar.HOUR, hour);
        System.out.println(hour+" hour");
        
        int minute = (int) (end.getTimeInMillis() - clone.getTimeInMillis()) / 60000;
        clone.add(Calendar.MINUTE, minute);
        System.out.println(minute+" minute");
        
        int millis = (int) (end.getTimeInMillis() - clone.getTimeInMillis()) / 1000;
        System.out.println(millis+" millis");

    }

    private static int elapsed(Calendar before, Calendar after, int field) {
        Calendar clone = (Calendar) before.clone();
        int elapsed = -1;
        while (!clone.after(after)) {
            clone.add(field, 1);
            elapsed++;
        }
        return elapsed;
    }

}
The code above generates the following result.