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Asked: 2026-05-16T07:25:30+00:00

My heart is bleeding internally after having to go so deep to subtract two

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My heart is bleeding internally after having to go so deep to subtract two dates to calculate the span in number of days:

    GregorianCalendar c1 = new GregorianCalendar();
    GregorianCalendar c2 = new GregorianCalendar();
    c1.set(2000, 1, 1);
    c2.set(2010,1, 1);
    long span = c2.getTimeInMillis() - c1.getTimeInMillis();
    GregorianCalendar c3 = new GregorianCalendar();
    c3.setTimeInMillis(span);
    long numberOfMSInADay = 1000*60*60*24;
    System.out.println(c3.getTimeInMillis() / numberOfMSInADay); //3653

where it’s only 2 lines of code in .NET, or any modern language you name.

Is this atrocious of java? Or is there a hidden method I should know?

Instead of using GregorianCalendar, is it okay to use Date class in util? If so, should I watch out for subtle things like the year 1970?

Thanks

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1 Answer

  1. Editorial Team

    It’s indeed one of the biggest epic failures in the standard Java API. Have a bit of patience, then you’ll get your solution in flavor of the new Date and Time API specified by JSR 310 / ThreeTen which is (most likely) going to be included in the upcoming Java 8.

    Until then, you can get away with JodaTime. 

    DateTime dt1 = new DateTime(2000, 1, 1, 0, 0, 0, 0);
DateTime dt2 = new DateTime(2010, 1, 1, 0, 0, 0, 0);
int days = Days.daysBetween(dt1, dt2).getDays();

    Its creator, Stephen Colebourne, is by the way the guy behind JSR 310, so it’ll look much similar.

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