how can i get Calendar.getInstance() based on Turkey timezone

I am developing an android application.
What should I do to get the current time based on Turkish local time?

val now = Calendar.getInstance(TimeZone.getTimeZone("GMT+3"))

the result is:

2020-08-25T18:16:30

but this website result is different:
https://www.timeanddate.com/worldclock/turkey/istanbul

2020-08-25T16:46:30

The output is printed using the following code snippet:

DebugHelper.info("one now => ${now.getDisplayMonthNameDayTime(FULL_PATTERN)}")

Extention Function:

const val FULL_PATTERN = "yyyy-MM-dd'T'HH:mm:ss"

fun Calendar.getDisplayMonthNameDayTime(pattern: String = "dd MMM , HH:mm ") = SimpleDateFormat(
    pattern,
    Locale.getDefault()
).format(time).toUpperCase(Locale.getDefault())

If you want to use a modern and less troublesome API, then use java.time, especially java.time.ZonedDateTime.

See this minimal example:

public static void main(String[] args) {
	ZonedDateTime istanbulDateTime = ZonedDateTime.now(ZoneId.of("Europe/Istanbul"));
	System.out.println(istanbulDateTime);
}

Output (some seconds ago):

2020-08-25T16:32:56.069+03:00[Europe/Istanbul]

As an alternative, there is ZoneId.of("Asia/Istanbul"), too, but the values only differ in the description of the continent. Just a matter of taste, I think.

EDIT
After your edit I realized you aren't relying on a time zone but rather an offset. That brings in another alternative from java.time, that is java.time.OffsetDateTime.

For the sake of completeness, here's a possible solution which only takes a ZoneOffset without the need to provide a zone by String:

public static void main(String[] args) {
	OffsetDateTime utcPlusThreeDateTime = OffsetDateTime.now(ZoneOffset.ofHours(3));
	System.out.println(utcPlusThreeDateTime);
}

which output (a few seconds ago)

2020-08-25T16:53:14.490+03:00

... and yes, since there's API desugaring in Android, you can use it with a suitable gradle plugin.

The solution

Use ZoneId.of("Asia/Istanbul") and a ZonedDateTime from java.time, the modern Java date and time API, as demonstrated in the answer by deHaar.

The problem

You problem is in this line:

).format(time).toUpperCase(Locale.getDefault())

time gives you the time of the Calendar object as a Date (another poorly designed and long outdated class that we should not use anymore). A Date hasn’t got any time zone, so the time zone and offset information from the Calendar is lost. So when you format this Date, you are using the time zone of the SimpleDateFormat, not the time zone of the Calendar.

Your Calendar’s time zone was GMT+03:00 alright. As others have mentioned, you should prefer Europe/Istanbul or Asia/Istanbul, though.

Links

• Oracle tutorial: Date Time explaining how to use java.time.
• Related question: TimeZone problem in Java (it might even be a duplicate?)

Turkey have an issue with real time in java...

you need to do you own hack with GMT+03

TimeZone.getTimeZone("GMT+03")

code:

TimeZone timeZone = TimeZone.getTimeZone("GMT+03");
Calendar calendar = Calendar.getInstance(timeZone);