Develop Reference

SimpleDateFormat shows wrong local Time

I want to store a string into a databse (SQLite) for an Android App with the current time and date. For that purpose I am using SimpleDateFormat. Unfortunately it does not show the correct time when. I tried two options.
First Option (from SimpleDateFormat with TimeZone)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z", Locale.getDefault());
sdf.format(new Date());
Second option (from Java SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'") gives timezone as IST)
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss'Z'");
sdf2.setTimeZone(TimeZone.getTimeZone("CEST"));
In both cases the time is just wrong. It is not the local time that my laptop or phone is showing but the output time is 2 hours earlier. How can I change that? I would like to have the current time of Berlin (CEST) that is also shown on my computer. I appreciate every comment.

Use Europe/Berlin instead of CEST and you will get the expected result.
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class Main {
public static void main(String[] args) {
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z");
sdf2.setTimeZone(TimeZone.getTimeZone("Europe/Berlin"));
System.out.println(sdf2.format(new Date()));
}
}
Output:
2020-09-27 18:38:04 +0200
A piece of advice:
I recommend you switch from the outdated and error-prone java.util date-time API and SimpleDateFormat to the modern java.time date-time API and the corresponding formatting API (package, java.time.format). Learn more about the modern date-time API from Trail: Date Time. If your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.
Using the modern date-time API:
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
public class Main {
public static void main(String[] args) {
ZonedDateTime zdt = ZonedDateTime.now(ZoneId.of("Europe/Berlin"));
// Default format
System.out.println(zdt);
// Some custom format
System.out.println(zdt.format(DateTimeFormatter.ofPattern("EEEE dd uuuu hh:mm:ss a z")));
}
}
Output:
2020-09-27T18:42:53.620168+02:00[Europe/Berlin]
Sunday 27 2020 06:42:53 pm CEST
The modern API will alert you whereas legacy API may failover:
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class Main {
public static void main(String[] args) {
ZonedDateTime zdt = ZonedDateTime.now(ZoneId.of("CEST"));
// ...
}
}
Output:
Exception in thread "main" java.time.zone.ZoneRulesException: Unknown time-zone ID: CEST
at java.base/java.time.zone.ZoneRulesProvider.getProvider(ZoneRulesProvider.java:279)
at java.base/java.time.zone.ZoneRulesProvider.getRules(ZoneRulesProvider.java:234)
at java.base/java.time.ZoneRegion.ofId(ZoneRegion.java:120)
at java.base/java.time.ZoneId.of(ZoneId.java:408)
at java.base/java.time.ZoneId.of(ZoneId.java:356)
at Main.main(Main.java:6)
As you can see, you get an exception in this case whereas SimpleDateFormat will give you undesirable result as shown below:
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;
public class Main {
public static void main(String[] args) {
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss Z");
sdf2.setTimeZone(TimeZone.getTimeZone("CEST"));
System.out.println(sdf2.format(new Date()));
}
}
Output:
2020-09-27 16:47:45 +0000
You might be wondering what this undesirable result refers to. The answer is: when SimpleDateFormat doesn't understand a time-zone, it failovers (defaults) to GMT (same as UTC) i.e. it has ignored CEST and applied GMT in this case (not a good feature IMHO 😊).

ISO 8601
Assuming that your SQLite hasn’t got a datetime datatype I recommend that you use ISO 8601 format, the international standard, for storing your date-times as strings to SQLite. Next, consider using java.time, the modern Java date and time API, for your date and time work. The two suggestions go nicely hand in hand. Common recommendations say to store date and time in UTC, but I understand that you prefer Europe/Berlin time.
ZoneId databaseTimeZone = ZoneId.of("Europe/Berlin");
ZonedDateTime now = ZonedDateTime.now(databaseTimeZone);
String databaseTime = now.format(DateTimeFormatter.ISO_OFFSET_DATE_TIME);
System.out.println(databaseTime);
Output from the above when running just now:
2020-09-27T15:54:21.53+02:00
I have on purpose included the offset from UTC in the string. This will allow anyone retrieving the string to convert the time to UTC or the time zone of their preference. If the user travels to India to see Taj Mahal and retrieves the data there, converting to India Standard Time is no problem. The offset also disambiguates times in the night in October when Berlin changes from summer time (DST) to standard time and the same clock times repeat. Times before the change will have offset +02:00, times after the change will have +01:00.
How can I change the format(?)
Edit: If you insist on your own format for information and human readability, build a formatter for that. The ZonedDateTime already has the time in your chosen time zone, so that time is also the one you will have when you format it:
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss Z");
String databaseTime = now.format(formatter);
Now the result is:
2020-09-27 16:22:23 +0200
Further edit: Since human readability is the only requirement for that column, go all-in on that and use java’s predefined localized format, for example:
DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.LONG)
.withLocale(Locale.GERMAN);
September 2020 19:06:03 MESZ
If it’s too long for you, use FormatStyle.MEDIUM instead.
Further further edit: And why? The question is whether 27. September 2020 19:06:03 MESZ is easier to read and understand correctly than 2020-09-27 16:22:23 +0200. You should make it as easy for yourself as you reasonably can. There is a point in including the offset, +0200, though, since it is unambiguous whereas a time zone abbreviation like MESZ is not guaranteed to be (many time zone abbreviations are ambiguous).
What went wrong in your code?
You are probably running your code on a computer with its time zone set to UTC (or some other time zone that is currently two hours behind Berlin time). In your second snippet you are trying to make up for this fact by setting the time zone of you formatter to CEST (Central European Summer Time). The way you are doing that is not what you want, and it also does not work. Both have to do with the fact that CEST is not a time zone. CEST is two hours ahead of UTC, and if it had worked, you would have got two hours ahead of UTC also during the standard time of year where Berlin is only 1 hour ahead of UTC, that is, the wrong time. Since CEST is not a time zone, TimeZone does not recognize it as a time zone. And this is as confusing as the TimeZone class is: instead of objecting, it tacitly gives you GMT, so you have got nowhere. I really recommend avoiding using that class. The correct time zone identifier for Berlin is Europe/Berlin, the one I am also using in my code. Time zone identifiers come in the region/city format.
Question: Doesn’t java.time require Android API level 26?
java.time works nicely on both older and newer Android devices. It just requires at least Java 6.
In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
On older Android either use desugaring or the Android edition of ThreeTen Backport. It’s called ThreeTenABP. In the latter case make sure you import the date and time classes from org.threeten.bp with subpackages.
Links
Oracle tutorial: Date Time explaining how to use java.time.
Java Specification Request (JSR) 310, where java.time was first described.
ThreeTen Backport project, the backport of java.time to Java 6 and 7 (ThreeTen for JSR-310).
Java 8+ APIs available through desugaring
ThreeTenABP, Android edition of ThreeTen Backport
Question: How to use ThreeTenABP in Android Project, with a very thorough explanation.
Wikipedia article: ISO 8601

Well, i faced the same issue a week ago and I figured out that the problem is in the TimeZone settings
If you are getting the date as a string and you need to format it to another format use the code below
public String getCalendarDate(String inputDate){
Date date = getDateFromSource(inputDate);
SimpleDateFormat formatter = new SimpleDateFormat("EEEE, d MMMM yyyy", Locale.getDefault());
formatter.setTimeZone(TimeZone.getDefault());
return formatter.format(date);
}
Date getDateFromSource(String apiDate){
Date newFormattedDate = null;
SimpleDateFormat parser = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.ENGLISH);
parser.setTimeZone(TimeZone.getTimeZone("UTC"));
try {
newFormattedDate = parser.parse(apiDate);
} catch (ParseException e) {
e.printStackTrace();
}
return newFormattedDate;
}
In the getDateFromSource function change the date format to the source format, while in the getCalendarDate function, change the format to your required format.
If you already have the Date object, you can ignore the getDateFromSource function and put it directly in the second one
For those who use Kotlin this is the equivalent code
fun getCalendarDate(apiDate: String): String{
val date = getDateFromApi(apiDate)
val formatter = SimpleDateFormat("EEEE, d MMMM yyyy", Locale.getDefault())
formatter.timeZone = TimeZone.getDefault()
return formatter.format(date)
}
private fun getDateFromApi(apiDate: String) :Date{
val parser = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.ENGLISH)
parser.timeZone = TimeZone.getTimeZone("UTC")
return parser.parse(apiDate)!!
}

Understanding specific UTC time format YYYY-MM-DDTHH:MM:SS.SSSZ

I have two related questions.
Assume a program running in (British Standard Time)BST generates a date time value for current time in UTC (YYYY-MM-DDTHH:MM:SS.SSSZ) format.
Also assume current time in London is 2016-06-01 12:33:54.
If the current time given by the program is 2016-06-01T11:33:54.000Z , is the program wrong?
How is summertime offset for BST noted in the corresponding time format for YYYY-MM-DDTHH:MM:SS.SSSZ
I assume YYYY-MM-DDTHH:MM:SS+0001. Am I correct ?

Firstly please have a read of the iso8601 information. It's becoming more common place to deal with times in different time zones (e.g. server time zone and client time zone) and the standard is really useful.
In particular please read about UTC or "Zulu" time here.
The program is correct, since the London time is one hour ahead of "UTC" time in summer
The trailing 'Z' is a short notation for UTC (Zulu). You could also write "+00:00" instead of 'Z'. The SS.SSS refer to seconds and milliseconds - not related to the time zone. In devnull's comment he shows you how to apply an offset for summer.
Edit:
There's been some discussion in the comments about whether iso8601 timezone includes timezone or not, and whether timezone will in fact be printed out.
This depends completely on the date/time implementation. If we are using SimpleDateFormat then timezone is supported and will be printed.
Here's a code example to illustrate
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
formatter.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println(formatter.format(new Date()));
formatter.setTimeZone(TimeZone.getTimeZone("Europe/London"));
System.out.println(formatter.format(new Date()));
Output
2016-06-02T12:53:14.924Z
2016-06-02T13:53:14.925+01:00
Naturally, if you are using a different date/time library such as joda-time, then the implentation details will be different.
Edit: As #DerrylThomas pointed out with SimpleDateFormat wise to use lower case y for years - unless it's intended to use week year - explained in a bit of detail in another answer to a similar question https://stackoverflow.com/a/56911450.

if the current time given by the program is 2016-06-01T11:33:54.000Z ,
is the program wrong?
The format is correct and conforms to ISO 8601 but it does not represent Europe/London time. In London, in 2016, the DST started at Sunday, March 27, 1:00 am and ended at Sunday, October 30, 2:00 am and therefore a date-time representation for Europe/London during this time should have a timezone offset of +01:00 hours. The Z at the end specifies Zulu time which is UTC time and thus has a timezone offset of +00:00 hours. The same instant can be represented for Europe/London as 2016-06-01T12:33:54+01:00.
java.time
The java.util date-time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to java.time, the modern date-time API* .
Even Joda-Time should not be used anymore. Notice the following note at the Home Page of Joda-Time
Joda-Time is the de facto standard date and time library for Java
prior to Java SE 8. Users are now asked to migrate to java.time
(JSR-310).
java.time API is based on ISO 8601 and the date-time string, 2016-06-01T11:33:54.000Z can be parsed into java.time.ZonedDateTime and java.time.OffsetDateTime without needing a date-time parsing/formatting type.
Demo:
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class Main {
public static void main(String[] args) {
ZonedDateTime zdt = ZonedDateTime.parse("2016-06-01T11:33:54.000Z");
System.out.println(zdt);
ZoneId zoneId = ZoneId.of("Europe/London");
ZonedDateTime zdtInLondon = zdt.withZoneSameInstant(zoneId);
System.out.println(zdtInLondon);
}
}
Output:
2016-06-01T11:33:54Z
2016-06-01T12:33:54+01:00[Europe/London]
How to deal with Daylight Saving Time (DST)?
As mentioned earlier, the date-time string, 2016-06-01T11:33:54.000Z can also be parsed into java.time.OffsetDateTime without needing a date-time parsing/formatting type. However, OffsetDateTime has been designed to deal with a fixed timezone offset whereas ZonedDateTime has been designed to deal with a timezone and thus it take care of DST automatically. You can convert a ZonedDateTime to OffsetDateTime using ZonedDateTime#toOffsetDateTime if required.
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu-MM-dd'T'HH:mm:ss.SSS z", Locale.ENGLISH);
String strDateTime = "2016-03-01T11:33:54.000 Europe/London";
ZonedDateTime zdt = ZonedDateTime.parse(strDateTime, dtf);
System.out.println(zdt);
strDateTime = "2016-06-01T11:33:54.000 Europe/London";
zdt = ZonedDateTime.parse(strDateTime, dtf);
System.out.println(zdt);
}
}
Output:
2016-03-01T11:33:54Z[Europe/London]
2016-06-01T11:33:54+01:00[Europe/London]
Notice how the timezone offset has automatically changed from Z to 01:00 to reflect DST change. On the other hand,
import java.time.OffsetDateTime;
public class Main {
public static void main(String[] args) {
String strDateTime = "2016-03-01T11:33:54.000+01:00";
OffsetDateTime odt = OffsetDateTime.parse(strDateTime);
System.out.println(odt);
strDateTime = "2016-06-01T11:33:54.000+01:00";
odt = OffsetDateTime.parse(strDateTime);
System.out.println(odt);
}
}
Output:
2016-03-01T11:33:54+01:00
2016-06-01T11:33:54+01:00
In this case, you do not talk about a timezone (e.g. Europe/London); rather, you talk about a fixed timezone offset of +01:00 hours.
Learn more about the modern date-time API from Trail: Date Time.
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

Working with various Calendar TimeZone in Java (without using Joda Time)

I was looking for a way to get current time in various timezones based on an user input. I know I could use Joda Time! but is that the only way?
Isn't there an option in Java for doing this? I tried the following code which gives the same output for all 3 sysouts.
Calendar pst = Calendar.getInstance(TimeZone.getTimeZone("PST"));
System.out.println("PST " + pst.getTime());
Calendar ist = Calendar.getInstance(TimeZone.getTimeZone("Asia/Calcutta"));
System.out.println("IST " + ist.getTime());
Calendar utc = Calendar.getInstance(TimeZone.getTimeZone("Etc/UTC"));
System.out.println("UCT " + utc.getTime());
What am I missing here to get current time in other timezones?

Yes, that would show the same value in every case (or milliseconds apart) because the three calendars all refer to the same instant in time (execution time notwithstanding) and that's all that a java.util.Date represents. That's the result of Calendar.getTime().
However, the Calendar itself does know about time zones, and that will be reflected when you use Calendar.get etc. It will also be used when you use a SimpleDateFormat, where you can specify a particular time zone.
// Specify whatever format you want - bear in mind different locales etc
SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss");
format.setTimeZone(calendar.getTimeZone());
String text = format.format(calendar.getTime());
It's not clear exactly what you're trying to do, but basically you need to be aware of which types are time zone aware, and which aren't. It's really important to understand that a java.util.Date doesn't have a format, a calendar system or a time zone: it's just the number of milliseconds since the Unix epoch.

As Jon pointed out the method getTime() is returning a java.util.Date object which is just a millisecond value and not timezone aware.
If you are just looking at printing the times then you can use the calendar and manually get the fields you want like
System.out.println(utc.get(Calendar.HOUR_OF_DAY) + ":" + utc.get(Calendar.MINUTE))
This would need some formatting for a minute < 10 to display the 0

java.time
The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API*.
Also, quoted below is a notice from the home page of Joda-Time:
Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.
Solution using java.time, the modern Date-Time API:
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
public class Main {
public static void main(String[] args) {
Instant now = Instant.now();
System.out.println(now);
ZonedDateTime zdtLos = now.atZone(ZoneId.of("America/Los_Angeles"));
ZonedDateTime zdtIndia = now.atZone(ZoneId.of("Asia/Kolkata"));
ZonedDateTime zdtUtc = now.atZone(ZoneOffset.UTC);
System.out.println(zdtLos);
System.out.println(zdtIndia);
System.out.println(zdtUtc);
}
}
Output from a sample run:
2021-07-26T12:39:17.413671-07:00[America/Los_Angeles]
2021-07-27T01:09:17.413671+05:30[Asia/Kolkata]
2021-07-26T19:39:17.413671Z
ONLINE DEMO
An Instant represents an instantaneous point on the timeline, normally represented in UTC time. The Z in the output is the timezone designator for a zero-timezone offset. It stands for Zulu and specifies the Etc/UTC timezone (which has the timezone offset of +00:00 hours).
For any reason, if you need to convert this object of Instant to an object of java.util.Date, you can do so as follows:
Date date = Date.from(instant);
Learn more about the modern Date-Time API from Trail: Date Time.
Never use the 3-letter abbreviated timezone ID
Given below is an excerpt from the documentation page of TimeZone:
For compatibility with JDK 1.1.x, some other three-letter time zone
IDs (such as "PST", "CTT", "AST") are also supported. However, their
use is deprecated because the same abbreviation is often used for
multiple time zones (for example, "CST" could be U.S. "Central
Standard Time" and "China Standard Time"), and the Java platform can
then only recognize one of them.
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

why this date is created with a different timezone?

This code:
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-DD_HH-mm-ss");
Date date=null;
try {
date = format.parse("2012-07-04_13-42-03");
} catch (Exception e) {
}
File file = new File("File.txt");
Date now=new Date();
Date last= new Date(file.lastModified());
System.out.println("exec:"+date+" "+date.getTime()+" "+date.getTimezoneOffset());
System.out.println(" now:"+now+" "+now.getTime()+" "+now.getTimezoneOffset());
System.out.println("last:"+last+" "+last.getTime()+" "+last.getTimezoneOffset());
gives the result:
exec:Wed Jan 04 13:42:03 CET 2012 1325680923000 -60
now:Wed Jul 04 13:42:20 CEST 2012 1341402140349 -120
last:Mon Jul 02 17:26:37 CEST 2012 1341242797000 -120
How can I create the date from the string so I can compare It with the rest, in the same timezone?

Date doesn't have a time zone. What's confusing you is that Date.toString() always returns a value formatted in the system default time zone, and that's what Date.getTimeZoneOffset does as well.
Now, in your system default time zone (Central European time, by the looks of it) the offset from UTC changes over the course of the year, as does the time zone abbreviation. That's what you're seeing: the difference between "Central European" time (UTC+1) and "Central European Summer Time") (UTC+2). That's the time zone information in the current system time zone for the instant in time represented by the Date value you're converting into a string representation.
Again, the Date itself has no information about the time zone. It's just a point in time. You can set the time zone that the SimpleDateFormat uses when parsing or formatting - that's a different matter.
You should also consider using Joda Time if at all possible - it's much better than the API built into Java.

Ok,
so the problem wasn't the timezone, but the conversion from
2012-07-04_13-42-03
to
Wed Jan 04 13:42:03 CET 2012
the problem is in the format pattern so changing
yyyy-MM-DD_HH-mm-ss
to
yyyy-MM-dd_HH-mm-ss
since D means Day in year and d means Day in month

java.time
The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API*.
Also, quoted below is a notice from the home page of Joda-Time:
Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.
Solution using java.time, the modern Date-Time API:
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
String strDateTime = "2012-07-04_13-42-03";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("u-M-d_H-m-s", Locale.ENGLISH);
LocalDateTime ldt = LocalDateTime.parse(strDateTime, dtf);
System.out.println(ldt);
}
}
Output:
2012-07-04T13:42:03
ONLINE DEMO
How to compare two LocalDateTimes:
You can use LocalDateTime#isAfter and LocalDateTime#isBefore to compare two LocalDateTimes.
Learn more about the modern Date-Time API from Trail: Date Time.
What went wrong with your code?
You have used D which specifies Day in year whereas you need d which specifies Day in month. Since you are comparing all the Date-Times in the same timezone, there is no problem with the timezone in this case.
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.

Difference between EST and America/New_York time zones

Can somebody please tell, what's the difference between the following two statements:
TimeZone.getTimeZone("America/New_York")
and
TimeZone.getTimeZone("EST")
In other words, why is EST different from America/New_York. Also in my application, to get the current time zone in US, should I use America/New_York or EST.

EST is UTC - 5 hours. America/New_York is EST in the winter and E*D*T in the summer, so right now New York is UTC - 4 hours.

EST is half of the New York time zone, effectively. It's always in standard time - it doesn't have the daylight saving part. It's not really a proper time zone in its own right, IMO - it's the "standard" part of a fuller time zone. When writing about a time zone which is just a fixed offset and not related to a particular place, I'd prefer to use "Etc/GMT+5" or something similarly obviously-fixed. (I don't generally like even "Eastern Time" and the like, as different places which observe "Eastern Time" may vary in their DST transitions. It's a bit like calling an encoding "extended ASCII"... it tells you some information, but not quite enough.)
So if you want to know the actual local time for New York at any particular instant, use America/New_York.
In general, stay away from the abbreviations. From the documentation:
For compatibility with JDK 1.1.x, some other three-letter time zone IDs (such as "PST", "CTT", "AST") are also supported. However, their use is deprecated because the same abbreviation is often used for multiple time zones (for example, "CST" could be U.S. "Central Standard Time" and "China Standard Time"), and the Java platform can then only recognize one of them.
(Personally I'd also advise you to stay away from Date and Calendar, preferring to use Joda Time wherever possible. That's a different matter though, really.)

The timezone, America/New_York observes two different timezone offsets:
EST (winter time): has a timezone offset of -05:00 hours
EDT (summer time): has a timezone offset of -04:00 hours
java.time
The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API*.
Also, quoted below is a notice from the home page of Joda-Time:
Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.
What Date-Time object should I use to adjust the offset automatically?
Use ZonedDateTime which has been designed to adjust the timezone offset automatically.
Demo:
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.Month;
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class Main {
public static void main(String[] args) {
ZoneId zoneId = ZoneId.of("America/New_York");
// Custom times
ZonedDateTime zdtDstOn = ZonedDateTime.of(LocalDate.of(2020, Month.OCTOBER, 22), LocalTime.MIN, zoneId);
ZonedDateTime zdtDstOff = ZonedDateTime.of(LocalDate.of(2020, Month.NOVEMBER, 22), LocalTime.MIN, zoneId);
System.out.println(zdtDstOn);
System.out.println(zdtDstOff);
// Current time
ZonedDateTime zdtNow = ZonedDateTime.now(zoneId);
System.out.println(zdtNow);
}
}
Output:
2020-10-22T00:00-04:00[America/New_York]
2020-11-22T00:00-05:00[America/New_York]
2021-08-17T12:19:41.854781-04:00[America/New_York]
ONLINE DEMO
Avoid using the abbreviated timezone names
The following quote from the documentation states the problem clearly:
Three-letter time zone IDs
For compatibility with JDK 1.1.x, some
other three-letter time zone IDs (such as "PST", "CTT", "AST") are
also supported. However, their use is deprecated because the same
abbreviation is often used for multiple time zones (for example, "CST"
could be U.S. "Central Standard Time" and "China Standard Time"), and
the Java platform can then only recognize one of them.
Then, what Date-Time object should I use for a fixed timezone offset?
Use OffsetDateTime for a fixed timezone offset.
Demo:
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.Month;
import java.time.OffsetDateTime;
import java.time.ZoneOffset;
public class Main {
public static void main(String[] args) {
ZoneOffset zoneOffset = ZoneOffset.of("-04:00");
// A custom time
OffsetDateTime odt = OffsetDateTime.of(LocalDate.of(2020, Month.OCTOBER, 22), LocalTime.MIN, zoneOffset);
System.out.println(odt);
// Current time
OffsetDateTime odtNow = OffsetDateTime.now(zoneOffset);
System.out.println(odtNow);
}
}
Output:
2020-10-22T00:00-04:00
2021-08-17T12:36:09.123599-04:00
ONLINE DEMO
Note: For any reason, if you need to convert an object of OffsetDateTime or ZonedDateTime to an object of java.util.Date, you can do so as follows:
Date date = Date.from(odtNow.toInstant());
or
Date date = Date.from(zdtNow.toInstant());
Learn more about the modern Date-Time API* from Trail: Date Time.
Check this answer and this answer to learn how to use java.time API with JDBC.
* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.