Unexpected result on Subtracting Times

0 votes

If I run the following program, which parses two date strings referencing times 1 second apart and compares them:

public static void main(String[] args) throws ParseException {
    SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
    String str3 = "1927-12-31 23:54:07";  
    String str4 = "1927-12-31 23:54:08";  
    Date sDt3 = sf.parse(str3);  
    Date sDt4 = sf.parse(str4);  
    long ld3 = sDt3.getTime() /1000;  
    long ld4 = sDt4.getTime() /1000;
    System.out.println(ld4-ld3);
}

The output is:

353

Why is ld4-ld3 not 1 (as I would expect from the one-second difference in the times), but 353?

If I change the dates to times 1 second later:

String str3 = "1927-12-31 23:54:08";  
String str4 = "1927-12-31 23:54:09";  

Then ld4-ld3 will be 1.


Java version:

java version "1.6.0_22"
Java(TM) SE Runtime Environment (build 1.6.0_22-b04)
Dynamic Code Evolution Client VM (build 0.2-b02-internal, 19.0-b04-internal, mixed mode)

Timezone(`TimeZone.getDefault()`):

sun.util.calendar.ZoneInfo[id="Asia/Shanghai",
offset=28800000,dstSavings=0,
useDaylight=false,
transitions=19,
lastRule=null]

Locale(Locale.getDefault()): zh_CN

May 29, 2018 in Java by developer_1
• 3,310 points
200 views

1 answer to this question.

0 votes

ou've encountered a local time discontinuity:

When local standard time was about to reach Sunday, 1. January 1928, 00:00:00 clocks were turned backward 0:05:52 hours to Saturday, 31. December 1927, 23:54:08 local standard time instead

This is not particularly strange and has happened pretty much everywhere at one time or another as timezones were switched or changed due to political or administrative actions.

answered May 29, 2018 by Rishabh
• 3,620 points

Related Questions In Java

+4 votes
3 answers

What are the steps to set Java_home on Windows?

Set Java Home JAVA_HOME = C:\Program Files\Java\jdk1.7.0 [Location ...READ MORE

answered Sep 18, 2018 in Java by Sushmita
• 6,900 points
472 views
0 votes
1 answer

Is it possible to run a java program from command line on windows?How?

  Let's say your file is in C:\myprogram\ Run ...READ MORE

answered Apr 18, 2018 in Java by sophia
• 1,400 points
1,645 views
0 votes
1 answer

How to read and write on an excel files?

Follow these steps: Write: public class User { ...READ MORE

answered May 15, 2018 in Java by Rishabh
• 3,620 points
860 views
+1 vote
13 answers

How to send HTTP POST requests on Java?

With Apache HttpClient In the old days, this Apache ...READ MORE

answered Dec 10, 2020 in Java by Rajiv
• 8,910 points
143,130 views
0 votes
1 answer

Why is subtracting these two times (in 1927) giving a strange result?

In TZDB 2014f, the time of the ...READ MORE

answered Dec 21, 2020 in Java by Gitika
• 65,850 points
81 views
0 votes
3 answers

Convert date object to a String

We parse the full date to time ...READ MORE

answered Jul 31, 2018 in Java by samarth295
• 2,220 points
700 views
0 votes
2 answers

Date format conversion in Java

Calendar cal = Calendar.getInstance(); cal.add(Calendar.DATE, 1); Date date = ...READ MORE

answered Aug 13, 2018 in Java by Sushmita
• 6,900 points
318 views
0 votes
3 answers

Change date format in a Java string

The reason for the inaccuracy is because ...READ MORE

answered Feb 9 in Java by Soham
• 8,730 points
1,097 views
0 votes
1 answer

Perform "Switch-case" on String in Java

Switches based on integers can be optimized ...READ MORE

answered May 8, 2018 in Java by Rishabh
• 3,620 points
266 views
0 votes
2 answers

Result of character addition in Java

Binary arithmetic operations on char and byte ...READ MORE

answered Aug 22, 2019 in Java by Sirajul
• 59,170 points
2,309 views
webinar REGISTER FOR FREE WEBINAR X
Send OTP
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP