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POHow to get number of months, weeks, days and hours from now to a future time?
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  1. POHow to get number of months, weeks, days and hours from now to a future time?
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    copied!<p>I need to find out the number of months, weeks, days and hours left from now to a future time using Java. I can not use any third party library like Joda. How can I do that using just JDK classes? </p> <p>So far, this is what I have come up with. It sort of works, except for some situations:</p> <pre><code>public class DateUtil { public static Integer[] components(Date from, Date to) { Integer[] result = new Integer[4]; //SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm"); //df.setTimeZone(TimeZone.getTimeZone("EST")); Calendar fromCal = new GregorianCalendar(); Calendar toCal = new GregorianCalendar(); fromCal.setTime(from); toCal.setTime(to); int months = 0; do { fromCal.add(Calendar.MONTH, 1); ++months; //System.out.println(df.format(fromCal.getTime())); } while (fromCal.before(toCal)); fromCal.add(Calendar.MONTH, -1); --months; int days = 0; do { fromCal.add(Calendar.DAY_OF_YEAR, 1); ++days; } while (fromCal.before(toCal)); fromCal.add(Calendar.DAY_OF_YEAR, -1); --days; int hours = 0; do { fromCal.add(Calendar.HOUR_OF_DAY, 1); ++hours; } while (fromCal.before(toCal)); fromCal.add(Calendar.HOUR_OF_DAY, -1); --hours; int minutes = 0; do { fromCal.add(Calendar.MINUTE, 1); ++minutes; } while (fromCal.before(toCal)); result[0] = months; result[1] = days; result[2] = hours; result[3] = minutes; return result; } public static void main(String[] args) { try { SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm"); df.setTimeZone(TimeZone.getTimeZone("EST")); Date from = df.parse("2014-03-29 00:00"); Date to = df.parse("2014-05-29 00:00"); Integer result[] = components(from, to); System.out.printf("Months:%02d Days:%02d Hrs:%02d Mins:%02d\n", result[0], result[1], result[2], result[3]); } catch (Exception e) { e.printStackTrace(); } } } </code></pre> <p>It produces unacceptable results when you have February in the middle and start date is end of the month. For example:</p> <p>From: Dec 31, 2013 To: Dec 31, 2014</p> <p>The difference will produce: 12 months, 3 days.</p>
 

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