import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;


public class TimeDiff {
    /**
     * (For testing purposes)
     *
     */
    public static void main(String[] args) {
	Date d1 = new Date();
	try { Thread.sleep(750); } catch(InterruptedException e) { /* ignore */ }	
	Date d0 = new Date(System.currentTimeMillis() - (1000*60*60*24*3)); // About 3 days ago
	long[] diff = TimeDiff.getTimeDifference(d0, d1);

	System.out.printf("Time difference is %d day(s), %d hour(s), %d minute(s), %d second(s) and %d millisecond(s)\n",
		diff[0], diff[1], diff[2], diff[3], diff[4]);
	System.out.printf("Just the number of days = %d\n",
		TimeDiff.getTimeDifference(d0, d1, TimeDiff.TimeField.DAY));
    }

    /**
     * Calculate the absolute difference between two Date without
     * regard for time offsets
     *
     * @param d1 Date one
     * @param d2 Date two
     * @param field The field we're interested in out of
     * day, hour, minute, second, millisecond
     *
     * @return The value of the required field
     */
    public static long getTimeDifference(Date d1, Date d2, TimeField field) {
	return TimeDiff.getTimeDifference(d1, d2)[field.ordinal()];
    }

    /**
     * Calculate the absolute difference between two Date without
     * regard for time offsets
     *
     * @param d1 Date one
     * @param d2 Date two
     * @return The fields day, hour, minute, second and millisecond
     */
    public static long[] getTimeDifference(Date d1, Date d2) {
	long[] result = new long[5];
	Calendar cal = Calendar.getInstance();
	cal.setTimeZone(TimeZone.getTimeZone("UTC"));
	cal.setTime(d1);

	long t1 = cal.getTimeInMillis();
	cal.setTime(d2);

	long diff = Math.abs(cal.getTimeInMillis() - t1);
	final int ONE_DAY = 1000 * 60 * 60 * 24;
	final int ONE_HOUR = ONE_DAY / 24;
	final int ONE_MINUTE = ONE_HOUR / 60;
	final int ONE_SECOND = ONE_MINUTE / 60;

	long d = diff / ONE_DAY;
	diff %= ONE_DAY;

	long h = diff / ONE_HOUR;
	diff %= ONE_HOUR;

	long m = diff / ONE_MINUTE;
	diff %= ONE_MINUTE;

	long s = diff / ONE_SECOND;
	long ms = diff % ONE_SECOND;
	result[0] = d;
	result[1] = h;
	result[2] = m;
	result[3] = s;
	result[4] = ms;

	return result;
    }

    public static void printDiffs(long[] diffs) {
	System.out.printf("Days:         %3d\n", diffs[0]);
	System.out.printf("Hours:        %3d\n", diffs[1]);
	System.out.printf("Minutes:      %3d\n", diffs[2]);
	System.out.printf("Seconds:      %3d\n", diffs[3]);
	System.out.printf("Milliseconds: %3d\n", diffs[4]);
    }

    public static enum TimeField {DAY,
	HOUR,
	MINUTE,
	SECOND,
	MILLISECOND;
    }
}