Why does adding minutes to 1900-01-01 00:00:00 results in a change in seconds?

Question

I work on an application that uses a java.util.Date to hold a time. Every time get 1900-01-01 as date. The application has a utility class for adding minutes to a time. On Linux I get 1900-01-01 08:51:32 as result when adding 9*60 + 32 = 572 minutes to 1900-01-01 00:00:00 where 1900-01-01 09:32:00 is expected. How is this difference possible?

This difference does not occur on Windows 7 or on Linux for 1901 or 2013.

Compiled/Tested with Java: 1.6.0_23-b05 and 1.7.0_11-b21
Linux version: 2.6.18-308.el5 #1 SMP Fri Jan 27 17:17:51 EST 2012 x86_64 x86_64 x86_64 GNU/Linux
Timezone: CEST

package nl.brandweer.test.calendar;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class CalendarTest {

        public static void main(String[] args) {
                System.out.println("Hello Mars");
                CalendarTest test = new CalendarTest();
                test.test1();
                test.test2();
                test.test3();
        }

        GregorianCalendar myCalendar;

        private void test1() {
                System.out.println("Test 1");
                this.myCalendar = new GregorianCalendar(1900, 0, 1, 0, 0, 0);
                System.out.println("myCalendar: " + myCalendar);
                System.out.println("myCalendar.getTime(): " + myCalendar.getTime());

                addMinutes(572);
                System.out.println("myCalendar.getTime(): " + myCalendar.getTime());
        }

        private void test2() {
                System.out.println("Test 2");
                this.myCalendar = new GregorianCalendar(1901, 0, 1, 0, 0, 0);
                System.out.println("myCalendar: " + myCalendar);
                System.out.println("myCalendar.getTime(): " + myCalendar.getTime());

                addMinutes(572);
                System.out.println("myCalendar.getTime(): " + myCalendar.getTime());
        }

        private void test3() {
                System.out.println("Test 3");
                this.myCalendar = new GregorianCalendar(2013, 0, 1, 0, 0, 0);
                System.out.println("myCalendar: " + myCalendar);
                System.out.println("myCalendar.getTime(): " + myCalendar.getTime());

                addMinutes(572);
                System.out.println("myCalendar.getTime(): " + myCalendar.getTime());
        }

        /**
         * Add minutes to Time.<p>
         * The date stays te same!
         * @param value Minutes
         */
        protected void addMinutes(int value) {
                int year  = getYear();
                int month = getMonth() - 1;
                int day   = getDay();

                this.myCalendar.add(Calendar.MINUTE, value);

                this.myCalendar.set(Calendar.YEAR, year);
                this.myCalendar.set(Calendar.MONTH, month);
                this.myCalendar.set(Calendar.DAY_OF_MONTH, day);
        }

        /**
         * @return The day of month
         */
        public int getDay() {
            return get(Calendar.DAY_OF_MONTH);
        }

        /**
         * @return Month [1..12]
         */
        public int getMonth() {
            return get(Calendar.MONTH) + 1;
        }

        public int getYear() {
            return get(Calendar.YEAR);
        }

        protected int get(int field) {
                return myCalendar.get(field);
        }

}

A work-a-round is to change the year to 1901 or 2013 while doing pure time calculations.

UPDATE: The same error occurs for 1900 with Linux in a Joda-time implementation.

[This](http://stackoverflow.com/questions/16409554/30-minute-error-in-java-date-calculation-in-year-1900-only) question might help. — devnull, Oct 23 '13 at 13:06

score 0 · Answer 1 · answered Oct 23 '13 at 13:10

0

The time offset for UTC accounts for the gap: UTC + 1:39:52h

see http://www.timeanddate.com/worldclock/timezone.html?n=101&syear=1900

answered Oct 23 '13 at 13:10

Farlan

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Adding 01:39:52 to 08:51:32 makes 10:31:24 (see http://www.unitarium.com/time-calculator) which is not equal to 09:32:00. Also the error does not occure in 1901 and the mentioned offset goes on till 1920. Am I missing something? – Michel Weber Oct 24 '13 at 05:13

Why does adding minutes to 1900-01-01 00:00:00 results in a change in seconds?

1 Answers1