Convert seconds since 01-01-1900 to timestamp in Brazil

Robert Kock :

I'm managing devices that report their system clock as seconds since midnight 01-01-1900.
I need to convert this into a timestamp.

So far, I'm doing this as follows:

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class TestTime
{
  // Pass seconds since 01-01-1900 00:00:00 on the command line
  public static void main(String[] args)
  {
    // ---------------------
    // Create time formatter
    // ---------------------
    SimpleDateFormat format;
    format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    // ---------------------------
    // Compose 01-01-1900 00:00:00
    // ---------------------------
    Calendar cal;
    cal = Calendar.getInstance();
    cal.set(Calendar.YEAR, 1900);
    cal.set(Calendar.MONTH, Calendar.JANUARY);
    cal.set(Calendar.DAY_OF_MONTH, 1);
    cal.set(Calendar.HOUR_OF_DAY, 0);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);

    // -------------------
    // Show what we've got
    // -------------------
    System.out.println(format.format(cal.getTime()));

    // ---------------------------------------------
    // Add the seconds as passed on the command line
    // ---------------------------------------------
    long secs = Long.parseLong(args[0]);
    while (secs > Integer.MAX_VALUE)
    {
      cal.add(Calendar.SECOND, Integer.MAX_VALUE);
      secs -= Integer.MAX_VALUE;
    }
    cal.add(Calendar.SECOND, (int)secs);

    // -------------------
    // Show what we've got
    // -------------------
    System.out.println(args[0] + " corresponds to " + format.format(cal.getTime()));

  } // main

} // class TestTime

When running this on my local PC (Italy, Windows 7), I get the following:

java -cp . TestTime 3752388800
1900-01-01 00:00:00
3752388800 corresponds to 2018-11-28 10:13:20

This is perfectly correct.
I get the same results when running this on a Linux machine (still in Italy).

However, running the very same program on a Linux machine in Brazil, I get different results:

java -cp . TestTime 3752388800
1900-01-01 00:00:00
3752388800 corresponds to 2018-11-28 11:19:48

Whatever value I pass on the commandline, the difference is always 01:06:28.
Any idea where this difference is coming from?

BTW, I'm not concerned about the timezone. I just need a timestamp

Update 1:
The very same thing happens also when using Java 6 (which is the actual version used within our production environment in Brazil).
So, the problem does not depend on the java version

Update 2:
The problem does not occur when entering a number of seconds below 441763200 (which corresponds to 01-01-1914 00:00:00) The question remains why we get a difference for Brazil?

Meini :

Have a look at this site: https://www.timeanddate.com/time/zone/brazil/sao-paulo and navigate to Time zone changes for: 1900-1924. There you can see an offset of -03:06:28 to UTC before 01-01-1914. It is exactly the same reason as in Why is subtracting these two times (in 1927) giving a strange result?

Convert seconds since 01-01-1900 to timestamp in Brazil

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