Question

I am trying to determine an age in years from a certain date. Does anyone know a clean way to do this in Android? I have the Java api available obviously, but the straight-up java api is pretty weak, and I was hoping that Android has something to help me out.

EDIT: The multiple recommendations to use Joda time in Android worries me a bit due to Android Java – Joda Date is slow and related concerns. Also, pulling in a library not shipped with the platform for something this size is probably overkill.

Answer 1

import java.util.Calendar;
import java.util.Locale;
import static java.util.Calendar.*;
import java.util.Date;

public static int getDiffYears(Date first, Date last) {
    Calendar a = getCalendar(first);
    Calendar b = getCalendar(last);
    int diff = b.get(YEAR) - a.get(YEAR);
    if (a.get(MONTH) > b.get(MONTH) || 
        (a.get(MONTH) == b.get(MONTH) && a.get(DATE) > b.get(DATE))) {
        diff--;
    }
    return diff;
}

public static Calendar getCalendar(Date date) {
    Calendar cal = Calendar.getInstance(Locale.US);
    cal.setTime(date);
    return cal;
}

Note: as Ole V.V. noticed, this won’t work with dates before Christ due how Calendar works.