Hi can any one explain why such abnormal behavior from Calendar .after method
Calendar cal = Calendar.getInstance();
Calendar cal1 = Calendar.getInstance();
cal.set(Calendar.HOUR, 14);
cal1.set(Calendar.HOUR, 13);
System.out.println(cal.after(cal1)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
cal.set(Calendar.DATE, Calendar.getInstance().get(Calendar.DATE));
System.out.println(cal.after(cal1)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
Output:
true Cal Tue Oct 01 02:55:16 IST 2019 cal1 Tue Oct 01 01:55:16 IST 2019
true Cal Wed Oct 30 02:55:16 IST 2019 cal1 Tue Oct 01 01:55:16 IST 2019
but I did not get why cal is after cal1 even if i have set cal1's date to current date,
so if cal is today, I assigned the time as 14 hr it mover to next date then i set the date as current date in cal while for cal1 i did not.
So why still cal.after(cal1) is showing true in second syso while my cal1 is clearly 1 day greater than cal?
any suggestion to resolve such problem? Use java.time
I agree with you that there are some surprises in your code. You may have intended this:
ZoneId zone = ZoneId.of("Asia/Kolkata");
ZonedDateTime zdt = ZonedDateTime.now(zone);
ZonedDateTime zdt1 = ZonedDateTime.now(zone);
zdt = zdt.withHour(14);
zdt1 = zdt1.withHour(13);
System.out.println(zdt.isAfter(zdt1) + " zdt " + zdt + " zdt1 " + zdt1);
zdt = zdt.withDayOfMonth(ZonedDateTime.now(zone).getDayOfMonth());
System.out.println(zdt.isAfter(zdt1) + " zdt " + zdt + " zdt1 " + zdt1);
Output when I ran the code just now:
true zdt 2019-09-30T14:44:13.630029+05:30[Asia/Kolkata] zdt1 2019-09-30T13:44:13.630362+05:30[Asia/Kolkata]
true zdt 2019-09-30T14:44:13.630029+05:30[Asia/Kolkata] zdt1 2019-09-30T13:44:13.630362+05:30[Asia/Kolkata]
I get true both times just as you got from your code, which shouldn’t be surprising. As others have said, 02:55h is after 01:55h, and Oct 30 is after Oct 01. Also, referring to my result, 14:44 is after 13:44. In both lines these two times are compared.
I am using java.time, the modern Java date and time API.
What went wrong in your code?
The surprises in your code stem from the Calendar class being poorly designed and often behaving differently from what we would immediately expect.
Why when you set the hour to 14, you get Tue Oct 01 02:55:16 IST 2019? The date has changed into the following month, and the hour of day is 2, not 14.
Why when you set the date to today’s date, September 30, you get October 30?
For 1., Calendar.HOUR refers to hour within AM or PM from 0 through 11. So setting it to 14 we should have expected an exception. A Calendar with standard settings doesn’t care. Since the time was already in PM, it extrapolates, so 14 PM becomes 2 AM on the next day. Since today is the last day of September, you get October 1.
For 2., Calendar.DATE doesn’t refer to the full date, but to the day of month. Since current day of month is 30 and we already had October1, we get October 30.
Long story short: Avoid the Calendar class. Use ZonedDateTime and/or other classes form java.time, the modern Java date and time API. They are so much nicer to work with and give far fewer surprises like the ones you experienced.
Link
Oracle tutorial: Date Time explaining how to use java.time.
Java docs for - Calendar.after()
public boolean after(Object when) {
return when instanceof Calendar && compareTo((Calendar)when) > 0;
}
//By definition :- true if the time of this Calendar is after the time represented by when; false otherwise.
System.out.println(cal.after(cal1)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
//true Cal Tue Oct 01 02:17:46 IST 2019 cal1 Tue Oct 01 01:17:46 IST 2019
cal.set(Calendar.HOUR, 13);
cal1.set(Calendar.HOUR, 14);
System.out.println(cal.after(cal1)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
//false Cal Tue Oct 01 01:16:55 IST 2019 cal1 Tue Oct 01 02:16:55 IST 2019
cal.set(Calendar.DATE, Calendar.getInstance().get(Calendar.DATE));
System.out.println(cal.after(cal1)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
//true Cal Wed Oct 30 13:17:46 IST 2019 cal1 Tue Oct 01 14:17:46 IST 2019
System.out.println(cal.after(cal1)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
//true Cal Tue Oct 01 02:25:19 MMT 2019 cal1 Tue Oct 01 01:25:19 MMT 2019
cal.set(Calendar.DATE, Calendar.getInstance().get(Calendar.DATE));
System.out.println(cal1.after(cal)+" Cal "+cal.getTime()+" cal1 "+cal1.getTime());
//false Cal Wed Oct 30 02:25:19 MMT 2019 cal1 Tue Oct 01 01:25:19 MMT 2019
Using
cal.setTime((Calendar.getInstance()).getTime());
instead of
cal.set(Calendar.DATE, Calendar.getInstance().get(Calendar.DATE));
gives the desired result.
Related
I want to get the max date of one month, that it's does't work in some day like the code, it's appear by condition as below
February has problem 2017 Feb Max is 28，If your computer's date is larger than 28, like 2017-03-29 or 2017-04-30
Date date = PrimeUtil.formatStringToTime("2017-02","yyyy-MM");
System.out.println(date);
Calendar c = Calendar.getInstance();
c.set(Calendar.YEAR,date.getYear());
c.set(Calendar.MONTH,date.getMonth());
c.set(Calendar.DAY_OF_MONTH,c.getActualMaximum(Calendar.DAY_OF_MONTH));
System.out.println(c.getTime());
I had your problem. The problem is that when you set the month, the day is shifted if needed.
I had a method:
public static Date getLastDayOfMounth(int month){
Calendar cTemp = Calendar.getInstance();
// here is where I need to set the day
cTemp.set(Calendar.MONTH, month);
cTemp.set(Calendar.DAY_OF_MONTH, cTemp.getActualMaximum(Calendar.DAY_OF_MONTH));
return cTemp.getTime();
}
I had a test unit for the method that test the method for each month, from 0 to 11. It has workt until today.
Today, 29 March 2018, the test case gone on error for february... why?
First cTemp = 29/03/2018 (today)
then cTemp.set(Calendar.MONTH, 1); is 29/02/2018 but this day does not esists, so became 01/03/2018
then cTemp.getActualMaximum(Calendar.DAY_OF_MONTH) is the last day of march.
I solved adding
cTemp.set(Calendar.DAY_OF_MONTH, 1);
before setting the month. So I start always from first day, avoid problem of skipping to the next month.
I solve the problem by myself,I flow the resource code find that If put February, and use c.set(Calendar.MONTH, date.getMonth()) that the GregorianCalendar have return a wrong time, it's maybe a bug of Calendar, I change my code like below, it will work well
Date date = PrimeUtil.formatStringToTime("2017-02","yyyy-MM");
System.out.println(date);
Calendar c = Calendar.getInstance();
c.setTime(date);
c.set(Calendar.DAY_OF_MONTH,c.getActualMaximum(c.DAY_OF_MONTH));
System.out.println(c.getTime());
the console will print:
Wed Feb 01 00:00:00 CST 2017
Tue Feb 28 00:00:00 CST 2017
It's looks like cause by the mythod c.set(Calendar.MONTH, date.getMonth());
I wasn't changing DAY_OF_MONTH, so as the current date is 29 March 2019, even I change month to February, but in 2019, February has only 28 days, so even after changing month to Feb, it was still considering March, to resolve this I have to set DAY_OF_MONTH to 1.
private fun getLengthOfMonth(year: Int, month: Int): Int {
val calendar = Calendar.getInstance()
calendar.set(Calendar.YEAR, year)
calendar.set(Calendar.MONTH, month - 1)
calendar.set(Calendar.DAY_OF_MONTH,1)
return calendar.getActualMaximum(Calendar.DAY_OF_MONTH)
}
Your case: the value of date is "2017-02", the value of c is: "2017-03-30"
date: 2017-02
c: 2017-03-30
c.set(Calendar.YEAR, date.getYear());
c.set(Calendar.MONTH, date.getMonth());
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));
=>
c.set(Calendar.YEAR, 2017);
c.set(Calendar.MONTH, 2);
c.set(Calendar.DAY_OF_MONTH, 31);
Here set 31 to DAY_OF_MONTH, Which could not get what you expected!
Another case:
the value of date is "2017-04", the value of c is: "2017-03-31"
date: 2017-04
c: 2017-05-31
When we set 31 to DAY_OF_MONTH, we will not get what we expected.
Recently New Zealand observed daylight saving on 27 sept 15.
SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd");
sd.setTimeZone(TimeZone.getTimeZone("Pacific/Auckland"));
Date dateValue = sd.parse("2015-09-30");
System.out.println(dateValue); // prints "Tue Sep 29 07:00:00 EDT 2015" My local system timzone in EDT
dateValue = DateUtils.addDays(dateValue, -6); // 6 days back 24 Sep of Pacific/Auckland
System.out.println(dateValue); // prints "Tue Sep 23 07:00:00 EDT 2015"
The second print statement should print Tue Sep 29 08:00:00 EDT 2015, as Daylight Saving not is in effect.
The issue is before 27 Sep 15 NZ = UTC+12
and after NZ = UTC +13
So on date of 23 Sep It should have time 08:00:00 not 07:00:00
The problem is within DateUtils.addDays from Apache Commons: it is using a Calendar with the default timezone to add and subtract days instead of using a user-supplied timezone. You can see this in the source code of the method add: it calls Calendar.getInstance() and not Calendar.getInstance(someTimezone)
If you construct yourself the Calendar and set the correct timezone, the problem disappears:
SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd");
sd.setTimeZone(TimeZone.getTimeZone("Pacific/Auckland"));
Date dateValue = sd.parse("2015-09-30");
System.out.println(dateValue); // prints "Tue Sep 29 13:00:00 CEST 2015"
Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("Pacific/Auckland")); // set correct timezone to calendar
calendar.setTime(dateValue);
calendar.add(Calendar.DAY_OF_MONTH, -6);
dateValue = calendar.getTime();
System.out.println(dateValue); // prints "Wed Sep 23 14:00:00 CEST 2015"
also i have used joda api to resolved this timezone issue.
org.joda.time.DateTimeZone timeZone = org.joda.time.DateTimeZone.forID( "Pacific/Auckland" );
DateTime currentDate= new DateTime( new Date(), timeZone );
DateTime dateValue = now.plusDays( -6 ); // prints Tue Sep 29 08:00:00 EDT 2015
From the below java code I'm getting a month First & last dateTimestamp, but here i need last dateTimestamp as - "Mon Aug 31 23:59:59 IST 2015" instead of - "Mon Aug 31 00:00:00 IST 2015"?
Calendar cal = Calendar.getInstance();
int year = 2015;
int month = 07;
cal.set(cal.DATE,1);
cal.set(cal.YEAR,year);
cal.set(cal.MONTH, month);
String firstDate = (cal.getActualMinimum(cal.DATE) + "/" + (month+1) + "/" +year);
System.out.println("firstDate-->"+"\t"+firstDate);
String lastDate = (cal.getActualMaximum(cal.DATE) + "/" + (month+1) + "/" +year);
System.out.println("lastDate-->"+"\t"+lastDate);
DateFormat firstFormat = new SimpleDateFormat("dd/MM/yyyy");
Date beginDate = firstFormat.parse(firstDate);
System.out.println("BeginDate Timestamp"+ "\t" + beginDate);
DateFormat secoundFormat = new SimpleDateFormat("dd/MM/yyyy");
Date endDate = secoundFormat.parse(lastDate);
System.out.println("endDate Timestamp"+ "\t" + endDate);
Output:->
firstDate--> 1/8/2015
lastDate--> 31/8/2015
BeginDate Timestamp Sat Aug 01 00:00:00 IST 2015
endDate Timestamp Mon Aug 31 00:00:00 IST 2015
Please help me if we have any solution.
If I understand your question, it looks as if you want to pass a year and month into a method, and get back the last day of the passed month.
I would suggest consider (in this order):
which jdk you use
configuration of calendar
configuration of timezone (maybe)
using jodatime
As of 1.8 many JodaTime-like features have been added to the jdk- e.g. see https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html (If you arent using 1.8 you can use the joda lib, assuming your organization allows it)
Calendar.getInstance() gives a default TimeZone and a default Locale, which means the definitions of the running JVM. You may or may not need to consider this and implement more than just getInstance(). See API javadoc.
Assuming a Gregeorian Calendar (hey, you could be Bahaian and have 19 months in the year ...) , here is one partial implementation using JDK 1.7, JodaTime jar 2.2, validation-1.0.0.GA jar:
#Test
public void testDate() {
final String dateStringOfFirstDay = "1.7.2015";
final Date lastDayOfMonth = getLastDayOfMonth(dateStringOfFirstDay);
Assert.assertNotNull(lastDayOfMonth);
//more assertions ...
}
private Date getLastDayOfMonth(#NotNull String dateStringOfFirstDay) {
//further validation here necessary according to required date format
DateTime dt = DateTime.parse(dateStringOfFirstDay);
return dt.dayOfMonth().withMaximumValue().toDate();
}
The defintion of DateFormat/DateTimeFormat and further result assertions is left up to you.
Best of luck!
Guys I got a solution for my question!!!
I think it will help u too...
Calendar calendar = Calendar.getInstance();
int year=2015;
int month=7;
int date=31;
int hourOfDay=23;
int minute=59;
int second=59;
int milliSecond=999;
calendar.set(year, month, date, hourOfDay, minute, second);
calendar.set(calendar.MILLISECOND, milliSecond);
System.out.println("Time from Calendar: "+calendar.getTime());
long timeInMilliSeconds=calendar.getTimeInMillis();
System.out.println("timeInMilliSeconds from calendar: "+timeInMilliSeconds);
Timestamp timestamp=new Timestamp(timeInMilliSeconds);
System.out.println(timestamp);
The above program gives the last date last timestamp in a selected month.
getTimeInMillis() takes the time from Jan 01, 1970 to current time in Milliseconds.
Using those milliseconds i'm getting the Timestamp.
Thank you for your help guys!!!
OutPut:->
Time from Calendar: Mon Aug 31 23:59:59 IST 2015
timeInMilliSeconds from calendar: 1441045799999
2015-08-31 23:59:59.999
I have a simple for my problem:
TimeZone fromTimeZone = TimeZone.getTimeZone("America/Santiago");
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, 8);
calendar.set(Calendar.MINUTE, 45);
calendar.set(Calendar.SECOND, 0);
calendar.set(Calendar.MILLISECOND, 0);
System.out.println(calendar.getTime() + " |Mili: " + calendar.getTimeInMillis());
The output: (My timezone is ICT)
Wed Apr 01 19:45:00 ICT 2015 |Milisecond: 1427892300000
The problem is: The calendar return wrong time for this Timezone on DST day. The timezone "America/Santiago" should be UTC-3 for now (ref: http://www.timeanddate.com/worldclock/chile/santiago.) . It need to show:
Wed Apr 01 18:45:00 ICT 2015 |Milisecond: 1427888700000
You have not applied the timezone fromTimeZone to the calendar .
Using Calendar I can get the week, year and all details for the current day. How can I navigate to a particualr day in that week?
Say, calendar.get(Calendar.DAY_OF_WEEK); returns 3, which means a Tuesday. Now, I want to go to say Friday for that week or any other day in that week. How can I do that?
Thanks for your replies. I think I need to make the scenario more clear.
Basically, I am trying to disable email alerts in my system during specified period.
I get values like:
disableStart = "FRIDAY-19:00"
disableEnd = "SUNDAY-19:00"
Now, i need to verify if email should be sent at a particular time.
e.g. if today = Thursday any time, send email
but, if today = Saturday any time can't send as per values above.
If I understand correctly you can use the Calendar.set(Field, value) method.
SimpleDateFormat f = new SimpleDateFormat("dd-MM-yyyy");
Calendar c = Calendar.getInstance();
System.out.println(c.get(Calendar.DAY_OF_WEEK));
System.out.println(f.format(c.getTime()));
c.set(Calendar.DAY_OF_WEEK, Calendar.TUESDAY);
System.out.println(c.get(Calendar.DAY_OF_WEEK));
System.out.println(f.format(c.getTime()));
Produces the output
6
08-10-2010
3
05-10-2010
Calendar c = Calendar.getInstance();
Date date = new Date();
c.setTime(date);
System.out.println("Today: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
System.out.println("MONDAY: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.TUESDAY);
System.out.println("TUESDAY: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.WEDNESDAY);
System.out.println("WEDNESDAY: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.THURSDAY);
System.out.println("THURSDAY: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);
System.out.println("FRIDAY: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);
System.out.println("SATURDAY: " + c.getTime());
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
System.out.println("SUNDAY: " + c.getTime());
Gives:
Today: Fri Oct 08 15:45:14 CEST 2010
MONDAY: Mon Oct 04 15:45:14 CEST 2010
TUESDAY: Tue Oct 05 15:45:14 CEST 2010
WEDNESDAY: Wed Oct 06 15:45:14 CEST 2010
THURSDAY: Thu Oct 07 15:45:14 CEST 2010
FRIDAY: Fri Oct 08 15:45:14 CEST 2010
SATURDAY: Sat Oct 09 15:45:14 CEST 2010
SUNDAY: Sun Oct 10 15:45:14 CEST 2010
Which seams to mean that, at least on my system, the weeks starts on monday.
cal.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);
Thanks to Kevin and Maurice for the answers. They really gave me the start point.
I ended with this test code, in case it helps anyone.
private static Date getTimeForAnyDayInWeek(int nDay, int nHour, int nMin)
{
Calendar c = Calendar.getInstance();
c.setFirstDayOfWeek(Calendar.MONDAY);
Date date = Calendar.getInstance().getTime();
c.setTime(date);
c.set(Calendar.DAY_OF_WEEK, nDay);
c.set(Calendar.HOUR_OF_DAY, nHour);
c.set(Calendar.MINUTE, nMin);
return c.getTime();
}
public static void main(String[] args)
{
Date start = getTimeForAnyDayInWeek(6, 19, 00);
Date end = getTimeForAnyDayInWeek(8, 19, 00);
Date c = new Date();
if (start.before(c) && c.before(end))
System.out.println("BLOCK");
else
System.out.println("SEND");
}
Thanks,
Anubhav
This is a perfect example of why jodatime is so good, here is my similar code
DateTime dt = new DateTime(); //current datetime, jodatime format
DateTime fridayLastWeek = dt.minusWeeks(1).dayOfWeek().setCopy("Friday");
Date convertedtorubbishdateformat = fridayLastWeek.toDate();
I used to waste so much time witht he standard java date/calendar. Then i got jodatime, you wont regret, it apparently will be used as part of standard java in the future. I didn;t bother downlaoding the jar for for ages, I wish I had done, you won't regret it.