Java Calendar find difference between two dates

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

public class Main {

   public static void main(String[] args) {
      // Obtain two instances of the Calendar class
      Calendar cal1 = Calendar.getInstance();
      Calendar cal2 = Calendar.getInstance();

      // Set the date to 01/01/2010:12:00
      cal2.set(2010, 0, 1, 12, 0);/*from   ww w  .ja v a 2 s. c  om*/
      Date date1 = cal2.getTime();
      System.out.println(date1);

      long mill = Math.abs(cal1.getTimeInMillis() - date1.getTime());
      // Convert to hours
      long hours = TimeUnit.MILLISECONDS.toHours(mill);
      // Convert to days
      
      Long days = TimeUnit.HOURS.toDays(hours);
      String diff = String.format("%d hour(s) %d min(s)", hours,TimeUnit.MILLISECONDS.toMinutes(mill) - TimeUnit.HOURS.toMinutes(hours));
      System.out.println(diff);

      diff = String.format("%d days", days);
      System.out.println(diff);

      // Divide the number of days by seven for the weeks
      int weeks = days.intValue() / 7;
      diff = String.format("%d weeks", weeks);
      System.out.println(diff);

   }
}