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Get Current TimeZone Abbrevation Android

Is there any library that I can get the current timezone abbrevation for Android like in this list: https://en.wikipedia.org/wiki/List_of_time_zone_abbreviations
For example, I am in Turkey and the timezone abbrevation for Turkey is TRT and I want to display it to user?
Here is the code I used so far:
fun getTimeZoneAbbrevation():String {
val id = TimeZone.getDefault().id
return ZoneId.of(id).getDisplayName(TextStyle.SHORT_STANDALONE, Locale.ENGLISH) }
And the result I get from this function is "Europe/Istanbul", what I except is TRT.

This should work:
val zone = ZonedDateTime.now(ZoneId.systemDefault()).zone
println(zone.getDisplayName(TextStyle.SHORT_STANDALONE, Locale.ENGLISH))
When I input Europe/Istanbul I get TRT:
val zone = ZoneId.of("Europe/Istanbul")
println(zone.getDisplayName(TextStyle.SHORT_STANDALONE, Locale.ENGLISH))
It would be extremely strange if the code wouldn't work on your system.
I have changed my default time zone to Istanbul and I am getting TRT when running the first block of code:

get tomorrow date 1:00pm in UNIX timestrap

Can't find any solution how to get tomorrow's date 13:00.
For example: today is 16.01.2019, I need to find how in unix timestrap is 17.01.2019 13:00.
tried this:
LocalDateTime tomorrowWithTime =
LocalDateTime.of(LocalDate.now().plusDays(1), 13:00);
to set manually 13:00, add it to tomorrows date and then convert to unix timestrap, but no luck :(

You were very close to it. To get the LocalDateTime it's
LocalDateTime tomorrowWithTime = LocalDateTime.of(LocalDate.now().plusDays(1), LocalTime.of(13, 0));
Then to convert it to unix timestamp please have a look at this question. In summary you have to give a ZoneId: (to give a working answer I'll use your system zoneId):
ZoneId zoneId = ZoneId.systemDefault(); //Or the appropriate zone
long timestamp = tomorrowWithTime.atZone(zoneId).toEpochSecond();
By the way, if your issue was that you didn't know what to give as parameters to LocalDateTime.of(), your first reflex should be to have a look at the API to see what parameters it accepts.

Timezone conversion in Grails leads to wrong dates

I'm about to deal with time zones in Grails (Java). Here Java 7 is used and Grails 2.3.7.
I have a WebApp where each user is assigned a timeZoneID. If a user enters a date, it only consists of day, month and year. I want to set the time automatically.
The date entered by the user (e.g. 01.10.2018, german format) should be saved in the DB (MySQL) in UTC format.
When the date is displayed to the user, it is formatted according to the user's time zone.
Many timeZoneIDs work fine with my code (Europe/Berlin, Hont_Kong, ....), but America/New_York for example doesn't and I don't understand why.
The code to parse and save a date is as follows:
//endDate is 31.10.2018
def format = messageService.getMessage(code: 'default.date.short.format')
//--> dd.MM.yyyy for DE and MM/dd/yy for EN
println("Use format: " + format)
SimpleDateFormat sdf = new SimpleDateFormat(format);
//set timezone (America/New_York)
sdf.setTimeZone(TimeZone.getTimeZone(user.timeZoneID))
//parse endDate
Date parsedEndDate = sdf.parse(endDate)
//create a calendar instance (e.g. America/New_York)
Calendar calendarEnd = Calendar.getInstance(TimeZone.getTimeZone(user.timeZoneID));
//set time
calendarEnd.setTime(parsedEndDate);
//set hour/minute automatically
calendarEnd.set(Calendar.HOUR_OF_DAY, 23)
calendarEnd.set(Calendar.MINUTE, 59)
//at this point it should be 31.10.2018, 23:59 (german format, timezone America/New_York)
//Convert to UTC before saving date in DB (MySQL)
calendarEnd.setTimeZone(TimeZone.getTimeZone('UTC'))
//save the date
def obj = new Foo(date:calendarEnd).save(flush:true)
The code inside my view (gsp) to display a date is as follows:
<g:formatDate
timeZone="${user.timeZoneID}"
date="${fooInstance?.calendarEnd}"
format="${message(code: 'default.date.format', default: 'MM/dd/yyyy, hh:mm a')}"/>
Inside the DB I get 2018-11-01 00:59:00
Inside my view (GSP) it results in 31.10.2018, 19:59, instead of 31.10.2018, 23:59
Thank you very much for your help.

The problem is in convert step:
//Convert to UTC before saving date in DB (MySQL)
calendarEnd.setTimeZone(TimeZone.getTimeZone('UTC'))
Because you are just changing the time zone so it is using the given time and date as if it is the UTC time zone.
Java 1.7 and before are somewhat unwieldy in regards to the Time API so a lot of people use Joda Time.
Otherwise you can use the advice from this question resulting in something like:
calendarEnd.add(Calendar.MILLISECOND, TimeZone.getTimeZone('UTC').getOffset(parsedEndDate.getTime())
This is not tested and could be wrong as the offset calculation might be diffrent

Java XMLGregorianCalendar format

I am currently stuck with XMLGregorianCalendar formatting problem and would like to seek help from you java gurus. With a function call from other system, I got a data object displayed on web page with "SUBMIT_DATE":1516032000000 and "SUBMIT_TIME":36895000 (both with returned type XMLGregorianCalendar). How can I know the correct human readable date and time in this case?
Thank you for your time and help.

Update after clarification
// We first need to check that the fields we need are defined
if (submitDate.getTimezone() == DatatypeConstants.FIELD_UNDEFINED) {
throw new IllegalStateException("No time zone defined in submit date " + submitDate);
}
if (submitDate.getYear() == DatatypeConstants.FIELD_UNDEFINED
|| submitDate.getMonth() == DatatypeConstants.FIELD_UNDEFINED
|| submitDate.getDay() == DatatypeConstants.FIELD_UNDEFINED) {
throw new IllegalStateException("Date not defined in submit date " + submitDate);
}
if (submitTime.getHour() == DatatypeConstants.FIELD_UNDEFINED
|| submitTime.getMinute() == DatatypeConstants.FIELD_UNDEFINED
|| submitTime.getSecond() == DatatypeConstants.FIELD_UNDEFINED) {
throw new IllegalStateException("Time of day not defined in submit time " + submitTime);
}
if (submitTime.getTimezone() != DatatypeConstants.FIELD_UNDEFINED
&& submitTime.getTimezone() != submitDate.getTimezone()) {
throw new IllegalStateException("Conflicting offsets " + submitDate.getTimezone()
+ " and " + submitTime.getTimezone() + " minutes");
}
// then format into a human readable string
final ZoneId userZone = ZoneId.of("Asia/Taipei");
final Locale userLocale = Locale.forLanguageTag("zh-TW");
DateTimeFormatter localizedFormatter = DateTimeFormatter
.ofLocalizedDateTime(FormatStyle.LONG)
.withLocale(userLocale);
ZonedDateTime dateTime = submitDate.toGregorianCalendar()
.toZonedDateTime()
.with(LocalTime.of(submitTime.getHour(), submitTime.getMinute(), submitTime.getSecond()))
.withZoneSameInstant(userZone);
String humanReadableDateTime = dateTime.format(localizedFormatter);
System.out.println(humanReadableDateTime);
This prints:
2018年1月16日 上午10時14分55秒
I am assuming that submitDate and submitTime are XMLGregorianCalendar objects that you have got from the complex object that you have received from a remote system. I am further assuming that you can require the date to contain a UTC offset. Though the method is called getTimezone, what it really returns is not a time zone, but an offset in minutes from UTC (or GMT). The extensive checks in the four if statements are necessary because XMLGregorianCalendar is very flexible with which fields are defined and which not.
To display the date and time in a format suitable for a user audience, you need to know that audience’s time zone and locale. Once you know those, please fill them in in the above snippet. If you trust the JVM’s settings, you may use ZoneId.systemDefault() and/or Locale.getDefault(Locale.Category.FORMAT) You may also choose between format styles FULL, LONG, MEDIUM and SHORT.
If you don’t receive an offset, you will need to rely on the date and time already being at the user’s offset. On one hand it’s simpler, on the other hand it is more fragile since if the date and time are given at another offset than the user expects, s/he will receive incorrect information, which is worse than receiving no information at all. First check that there is indeed no offset:
if (submitDate.getTimezone() != DatatypeConstants.FIELD_UNDEFINED
|| submitTime.getTimezone() != DatatypeConstants.FIELD_UNDEFINED) {
throw new IllegalStateException("Unexpected offset");
}
Also check that required fields are defined, this is the same as before. Then create a LocalDateTime object and format it:
LocalDateTime dateTime = LocalDateTime.of(
submitDate.getYear(), submitDate.getMonth(), submitDate.getDay(),
submitTime.getHour(), submitTime.getMinute(), submitTime.getSecond());
String humanReadableDateTime = dateTime.format(localizedFormatter);
I got the same result as above.
Original answer
final ZoneId userZone = ZoneId.of("Asia/Taipei");
final Locale userLocale = Locale.forLanguageTag("zh-TW");
ZonedDateTime submitDateTime
= Instant.ofEpochMilli(submitDate + submitTime).atZone(userZone);
DateTimeFormatter localizedFormatter = DateTimeFormatter
.ofLocalizedDateTime(FormatStyle.LONG)
.withLocale(userLocale);
String humanReadableDateTime = submitDateTime.format(localizedFormatter);
System.out.println(humanReadableDateTime);
This prints
2018年1月16日 上午10時14分55秒
To display the date and time in a format suitable for a user audience, you need to know that audience’s time zone and locale. Once you know those, please fill them in in the first two lines of the above snippet. If you trust the computer’s settings, you may use ZoneId.systemDefault() and/or Locale.getDefault(Locale.Category.FORMAT) You may also choose between format styles FULL, LONG, MEDIUM and SHORT. For this purpose I think you can ignore the information that the returned type is XMLGregorianCalendar.
As #user unknown in another answer I am assuming that you can just add the two numeric values. The first almost certainly denotes milliseconds since the epoch, the sum probably too. So why were they passed as two values and not just one? My best guess is that they pass the date separately for any client that just needs the date and not the time of day. The date value falls at midnight in time zones at offset +08:00, this would agree with China, Philippines, Malaysia and a dozen other time zones.
If instead of the numbers you have got two XMLGregorianCalendar objects, getting the date and time is a different story, but you may still use the same way of formatting them.

final GregorianCalendar calendar = new GregorianCalendar();
calendar.setTimeInMillis(date);
return DatatypeFactory.newInstance().newXMLGregorianCalendar(
calendar);
This should work..
Pass your millisecs

Your inputs look like they're just the date without time in milliseconds and the time without date in milliseconds.
If you divide both values by 1000:
date -d #1516032000
Mo 15. Jan 17:00:00 CET 2018
date -d #36895
Do 1. Jan 11:14:55 CET 1970
Well - but why 17:00:00? Maybe a time zone issue.
Here is the aggregate:
date -d #$((1516032000+36895))
Di 16. Jan 03:14:55 CET 2018
The various date/time formats for Java have methods, which take a long parameter for seconds since epoch (1.1.1970) to set the time.

Get Date and Time by Timezone; irrespective of machine's time

I am working on Spring MVC project. It is an quasi online system where each client will install our system (Tomcat n Mysql will get installed through an installer) on their machine. They will download the data by connecting their machine to internet. Once data get downloaded they can disconnect from internet.
By considering above scenario, we want to validate the system date n time is correct according to time zone. I have checked How to get local time of different time zones?, The code :
java.util.TimeZone tz = java.util.TimeZone.getTimeZone("IST");
java.util.Calendar c = java.util.Calendar.getInstance(tz);
System.out.println(c.get(java.util.Calendar.HOUR_OF_DAY)+":"+c.get(java.util.Calendar.MINUTE)+":"+c.get(java.util.Calendar.SECOND));
Give the same time of the system. I want something which will tell time according to the time zone. Same as like when we set time zone on OS clock it will automatically set the correct date and time according to that time zone.
Implementation like this:
Date accurateTimeZoneDate = //HERE I WANT SOMETHING TO GET DATE ACCORDING TO TIME ZONE.
Date machineCurrentDate = new Date();
if(accuratetimeZoneDate == machineCurrentDate)
{
//machine date and time zone date is correct.
}
else
{
//machine date and time zone date is NOT correct.
}
Update
We have tried this:
Daily it is mandatory to connect the system to internet so that application will ping to an central ntp and get the time and validate. once validation is successful then they can disconnect from internet. But in this case after validation they switch to some old date and use the expired content.

Ok if you want system time and date then you should try new Date().
it will give current date time with timezone.
Instead of using Calendar, you should use new Date()
System.out.println("Current Date And Time"+ new Date());