Here is the sample I am using.
import java.util.*;
import java.text.*;
public class TimeZoneTest
{
public static final String UTC_ZONE = "UTC";
static String utcDateString = "01/11/2016 11:00:00";
public static void main (String [] args)
{
DateFormat df;
try{
df = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
System.out.println("Original Date : " + utcDateString);
df.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = df.parse(utcDateString);
System.out.println(" In its Date format : " + date.toString());
System.out.println(" In its GMT format : " + date.toGMTString());
System.out.println(" In its Local format : " + date.toLocaleString());
}
catch (ParseException ex)
{
System.out.println("Exception!!!!");
}
}
}
Here is the output produced.
Original Date : 01/11/2016 11:00:00
In its Date format : Mon Jan 11 06:00:00 EST 2016
In its GMT format : 11 Jan 2016 11:00:00 GMT
In its Local format : Jan 11, 2016 6:00:00 AM
When using the time 11:00:00 and setting the TimeZone to UTC, I was expecting that the 11:00:00 which is my local time (Eastern) representation would then be converted to UTC which would produce 16:00:00.
Instead, it seems to take the string value 11:00:00 and process it as the UTC time instead of local time and return back my local time which is 06:00:00.
Is this the expected results?
When you set the timezone, is it supposed to convert the time being parsed (11:00:00 ) to that timezone and produce (16:00:00)?
OR
When you set the timezone, is it supposed to treat the time being parsed (11:00:00 ) as though it was in that timezone and return the local time (06:00:00)?
You're last statement is true: "OR When you set the timezone, is it supposed to treat the time being parsed (11:00:00 ) as though it was in that timezone and return the local time (06:00:00)?"
Basically, you set the timezone in the DateFormat, then you parse a date without timezone information, so it'll use the timezone from the DateFormat, to convert the String to certain amount of milliseconds from January 1, 1970. Then, you print that date with "toString" that will convert it back to String using your machine's timezone. But the date is the same throughout the program, just different format/timezone.
Related
I am converting from epoch time (which is in UTC) to a format as shown below. Now I tried different SO answers to convert UTCDate from UTC to local time. But I am not getting the local time.
Any help would be appreciated.
String epochTime = "1436831775043";
Date UTCDate = new Date(Long.parseLong(epochTime));
Date localDate; // How to get this?
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("h:mm a");
String result = simpleDateFormat.format(UTCDate);
Also, the conversion has to be done without the help of any external library.
Java 8
String epochTime = "1436831775043";
Instant utcInstant = new Date(Long.parseLong(epochTime)).toInstant();
ZonedDateTime there = ZonedDateTime.ofInstant(utcInstant, ZoneId.of("UTC"));
System.out.println(utcInstant);
LocalDateTime here = there.withZoneSameInstant(ZoneId.systemDefault()).toLocalDateTime();
System.out.println(here);
Which outputs:
2015-07-13T23:56:15.043Z
2015-07-14T09:56:15.043
After thoughts...
I think you're chasing your tail. Date is just a container for the number of milliseconds since the epoch (January 1, 1970, 00:00:00 GMT). It doesn't internally carry a representation of a time zone (AFAIK).
For example...
String epochTime = "1436831775043";
Date UTCDate = new Date(Long.parseLong(epochTime));
// Prints the "representation" of the Date
System.out.println(UTCDate);
// Local date/time format...
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd/MM/yyyy h:mm:ss a");
try {
System.out.println("local format: " + simpleDateFormat.format(UTCDate));
System.out.println("local Date: " + simpleDateFormat.parse(simpleDateFormat.format(UTCDate)));
} catch (ParseException ex) {
Logger.getLogger(JavaApplication203.class.getName()).log(Level.SEVERE, null, ex);
}
// UTC date/time format
try {
simpleDateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
System.out.println("utc format: " + simpleDateFormat.format(UTCDate));
System.out.println("utc date: " + simpleDateFormat.parse(simpleDateFormat.format(UTCDate)));
} catch (ParseException ex) {
Logger.getLogger(JavaApplication203.class.getName()).log(Level.SEVERE, null, ex);
}
Which outputs...
Tue Jul 14 09:56:15 EST 2015
local format: 14/07/2015 9:56:15 AM
local Date: Tue Jul 14 09:56:15 EST 2015
utc format: 13/07/2015 11:56:15 PM
utc date: Tue Jul 14 09:56:15 EST 2015
If you have a look at local Date and utc date they are the same thing, even though the local format and utc format are formatted correctly.
So, instead of chasing your tale trying to get Date to "represent" a value you want, either use Java 8's Time API or JodaTime to manage the Time Zone information or simply format the Date into the Time Zone you want...
Further, if we do something like...
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd/MM/yyyy h:mm:ss a");
Date localDate = simpleDateFormat.parse(simpleDateFormat.format(UTCDate));
simpleDateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
Date utcDate = simpleDateFormat.parse(simpleDateFormat.format(UTCDate));
System.out.println(localDate.getTime());
System.out.println(utcDate.getTime());
System.out.println(localDate.equals(utcDate));
It will print...
1436831775000
1436831775000
true
You can set your time zone in the formatter:
simpleDateFormat.setTimeZone(TimeZone.getDefault());
I am bit frustrated by this.
I have a String "2015-02-18T23:44:59" which represents time in GMT format.
I want to parse this date into date object.
String dateStr = "2015-02-18T23:44:59";
Date date = DateUtils.parseDate(dateStr, new String[]{"yyyy-MM-dd'T'HH:mm:ss"});
System.out.println(dateStr + " \t" + date.toString());
This outputs :
2015-02-18T23:44:59 Thu Feb 19 05:14:59 IST 2015
As you can see latter time has time zone IST but my original time was GMT.
I don't think there is any parse function which takes current date's time zone.
One way to answer is this question is that :
date.setTime(date.getTime() + ( date.getTimezoneOffset() * 60 * 1000));
System.out.println("\t" + date.toString());
This outputs:
Wed Feb 18 23:44:59 IST 2015
Which seems correct time (but incorrect time zone). Additionally, getTimezoneOffset() is deprecated.
Can anyone suggest me a better way to deal with String dates considering time zones.
I'd use a date format:
SimpleDateFormat utcFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
utcFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = utcFormat.parse("2015-02-18T23:44:59");
I have a String with timestamp in GMT. I want to convert this to a DateTime object in EST.
E.g If the string has:
final String gmtTime = "20140917-18:55:25"; // 4:55 PM GMT
I need to convert this to : 20140917-12:55:25 //12:55 PM EST
All these tries failed:
System.out.println("Time in GMT " + DateTimeFormat.forPattern("yyyyMMdd-HH:mm:ss").parseDateTime(gmtTime));
System.out.println("Time in EST " +
DateTimeFormat.forPattern("yyyyMMdd-HH:mm:ss").parseDateTime(gmtTime).withZone(DateTimeZone.forID("America/New_York")));
Output:
Time in GMT 2014-09-17T18:55:25.000-04:00
Time in EST 2014-09-17T18:55:25.000-04:00 //I expect: 2014-09-17T12:55:25.000-04:00
Any suggestions?
Joda-Time
Here a Joda-Time 2.4 solution:
String gmtTime = "20140917-18:55:25";
DateTime dateTimeGMT =
DateTimeFormat.forPattern("yyyyMMdd-HH:mm:ss").withZoneUTC().parseDateTime(gmtTime);
System.out.println("Time in GMT " + dateTimeGMT); // Time in GMT 2014-09-17T18:55:25.000Z
System.out.println(
"Time in EST "
+ DateTimeFormat.forPattern("yyyyMMdd-HH:mm:ss").withZone(
DateTimeZone.forID("America/New_York")
).print(dateTimeGMT)
); //Time in EST 20140917-14:55:25
I think that you have the wrong expectation regarding the result. EST (more correct to use is "America/New_York" as zone identifier) is four hours behind UTC, hence the local timestamp there is four hours earlier than the local representation of the same moment at UTC-offset.
Also note that I set the timezone on the formatter not on the parsed DateTime-object.
#Test
public void TimeZoneTest() {
Date now = new Date();
String DATE_PATTERN = "yyyyMMdd-HH:mm:ss";
DateFormat dfEST = new SimpleDateFormat(DATE_PATTERN);
dfEST.setTimeZone(TimeZone.getTimeZone("America/New_York"));
DateFormat dfGMT = new SimpleDateFormat(DATE_PATTERN);
dfGMT.setTimeZone(TimeZone.getTimeZone("GMT"));
System.out.println(dfEST.format(now));
System.out.println(dfGMT.format(now));
}
And the output is:
20140919-09:02:19
20140919-13:02:19
I'm trying to parse a date from a String and get the long value. The long value will be later sent to an SQL query.
here's my code:
String dayDate = "28-02-2013";
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
Date day = new Date();
try {
day = sdf.parse(dayDate);
} catch (ParseException pe) {
pe.printStackTrace();
}
System.out.println("day : "+day.toString()+ " long : " + day.getTime());
which gives the following output:
day : Thu Feb 28 00:00:00 EET 2013 long : 1362002400000
which is correct but not what I want since the long value results in Wed, 27 Feb 2013 22:00:00 GMT (http://www.epochconverter.com/) (I'm in a GMT+2 timezone). And i need to send to correct long value to sql.
Is there anyway to work around this without using external libraries?
SimpleDateFormat is locale-aware, meaning the date it parses is in your timezone. Midnight 28 Feb in GMT+2 is actually 10pm 27 Feb in GMT, the long value 1362002400000. I would add this to get the parsing right (would't bother using Calendar):
sdf.setTimeZone(TimeZone.getTimeZone("GMT"))
Again, when you print this date it uses SimpleDateFormat and that's why you can see EET in the output.
Passing this to database is a different story though once you get this right.
Use DateFormat.setCalendar(Calendar cal) to set a Calendar with GMT as its timezone, or use DateFormat.setTimeZone(TimeZone zone) with the GMT TimeZone. That will ensure that the resulting Date will be 00:00:00 in GMT instead of in EET.
If you add a timezone specifier to your string you can force java to use GMT for the conversion:
String dayDate = "28-02-2013";
SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy z"); // z is a timezone specifier
Date day = new Date();
try {
day = sdf.parse(dayDate + " GMT"); // Use GMT timezone.
} catch (ParseException pe) {
pe.printStackTrace();
}
System.out.println("day : "+day.toString()+ " long : " + day.getTime());
You are converting between text and internal (Date) representations of dates and times without explicitly stating the time-zone. That never goes well.
Calendar calendar = Calendar.getInstance();
calendar.setTimeZone(TimeZone.getTimeZone("America/Los_Angeles"));
Date date = calendar.getTime();
Use your timezone String:
TimeZones
I am trying to convert locale time to UTC, and then UTC to locale time. But I am not getting the result.
public class DateDemo
{
public static void main(String args[])
{
DateFormat dateFormatter =
DateFormat.getDateTimeInstance
(DateFormat.SHORT, DateFormat.SHORT, Locale.getDefault());
TimeZone.setDefault(TimeZone.getDefault());
SimpleDateFormat simpleDateFormatter = new SimpleDateFormat("dd/MM/yyyy");
SimpleDateFormat simpleTimeFormatter = new SimpleDateFormat("hh:mm:ss a");
Date today = new Date();
String localeFormattedInTime = dateFormatter.format(today);
try
{
Date parsedDate = dateFormatter.parse(localeFormattedInTime);
System.out.println("Locale:" + localeFormattedInTime);
System.out.println("After parsing a date: " + parsedDate);
simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());
String date = simpleDateFormatter.format(today);
String time = simpleTimeFormatter.format(today);
System.out.println("Today's only date: " + date);
System.out.println("Today's only time: " + time);
//// Locale to UTC converting
simpleDateFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
simpleTimeFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
String utcDate = simpleDateFormatter.format(today);
String utcTime = simpleTimeFormatter.format(today);
System.out.println("Convert into UTC's date: " + utcDate);
System.out.println("Convert into UTC's only time: " + utcTime);
//// UTC to locale converting
simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());
Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);
String getLocalDate = simpleDateFormatter.format(getDate);
String getLocalTime = simpleTimeFormatter.format(getTime);
System.out.println("Get local date: " + getLocalDate);
System.out.println("Get local time: " + getLocalTime);
} catch (ParseException e) {
e.printStackTrace();
}
}
}
I am sending local date & time to the web service, and then when require I need to retrieve the UTC date & time and then convert into locale date & time (i.e. user's local settings).
Sample Output:
Locale:11/9/12 8:15 PM
After parsing a date: Fri Nov 09 20:15:00 SGT 2012
Today's only date: 09/11/2012
Today's only time: 08:15:30 PM
Convert into UTC's date: 09/11/2012
Convert into UTC's only time: 12:15:30 PM
Get local date: 09/11/2012
Get local time: 12:15:30 PM
After Saksak & ADTC answers:
For the code fragment, UTC date & time (what is actually coming as GMT-5 because database may be in USA) is the input, and I want to get local date & time as output. But this following segment is still giving GMT-5 time.
SimpleDateFormat simpleDateTimeFormatter = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss a");
....
Date inDateTime = simpleDateTimeFormatter.parse(intent.getExtras().getString("inTime")); Date outDateTime = simpleDateTimeFormatter.parse(intent.getExtras().getString("outTime"));
simpleDateTimeFormatter.setTimeZone(TimeZone.getDefault()); simpleDateTimeFormatter.setTimeZone(simpleDateTimeFormatter.getTimeZone());
//TimeZone tzTimeZone = TimeZone.getDefault();
//System.out.println("Current time zone: " + tzTimeZone.getDisplayName());
String getLocalInTimeString = simpleDateTimeFormatter.format(inDateTime);
String getLocalOutTimeString = simpleDateTimeFormatter.format(outDateTime);
My question: getLocalInTimeString & getLocalOutTimeString still showing GMT-5 timing. What's wrong here? Do I need to set any other things?
What you need to do to solve your problem is the following, you have your code to convert back to local time in this order :
simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());
Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);
and what you need to do is wait until you parse utcDate, utcTime Strings back to Date Object
then set the date formatter time zone to local zone as follows :
Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);
simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());
this should print the correct date/time in local.
Edit:
here is the full main method :
public static void main(String[] args) {
DateFormat dateFormatter = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, Locale.getDefault());
TimeZone.setDefault(TimeZone.getDefault());
SimpleDateFormat simpleDateFormatter = new SimpleDateFormat("dd/MM/yyyy");
SimpleDateFormat simpleTimeFormatter = new SimpleDateFormat("hh:mm:ss a");
Date today = new Date();
String localeFormattedInTime = dateFormatter.format(today);
try {
Date parsedDate = dateFormatter.parse(localeFormattedInTime);
System.out.println("Locale:" + localeFormattedInTime);
System.out.println("After parsing a date: " + parsedDate);
simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());
String date = simpleDateFormatter.format(today);
String time = simpleTimeFormatter.format(today);
System.out.println("Today's only date: " + date);
System.out.println("Today's only time: " + time);
//// Locale to UTC converting
System.out.println("TimeZone.getDefault() >>> " + TimeZone.getDefault());
simpleDateFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
simpleTimeFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
String utcDate = simpleDateFormatter.format(today);
String utcTime = simpleTimeFormatter.format(today);
System.out.println("Convert into UTC's date: " + utcDate);
System.out.println("Convert into UTC's only time: " + utcTime);
//// UTC to locale converting
/**
** //////EDIT
*/
// at this point your utcDate,utcTime are strings that are formated in UTC
// so first you need to parse them back to Dates using UTC format not Locale
Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);
// NOW after having the Dates you can change the formatters timezone to your
// local to format them into strings
simpleDateFormatter.setTimeZone(TimeZone.getDefault());
simpleTimeFormatter.setTimeZone(TimeZone.getDefault());
String getLocalDate = simpleDateFormatter.format(getDate);
String getLocalTime = simpleTimeFormatter.format(getTime);
System.out.println("Get local date: " + getLocalDate);
System.out.println("Get local time: " + getLocalTime);
} catch (ParseException e) {
e.printStackTrace();
}
}
Your problem is in lines 54 and 55:
Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);
These lines are merely parsing Strings that contain the date and time, but these strings do not have any timezone information:
utcDate = "09/11/2012"
utcTime = "12:15:30 PM"
Therefore the parser assumes that the Strings are already in the locale of the timezone you set in lines 51 and 52.
Now think about how to fix it ;) HINT: Make sure the parser is assuming the correct timezone of the time represented by the strings.
PS: [RESOLVED!] I solved the problem but I discovered that the timezone conversion is erratic, for at least where I am. Time is 8:30 pm local. Convert to UTC, 12:30 pm (correct, 8 hr difference). Convert back, it's 8:00 pm (WRONG, eventhough the set timezone is correct - I got the original one and passed it back in - I'm only getting 7.5 hour difference). You should look for more reliable ways unless you can figure out what's going on and how to solve it.
[RESOLUTION:] The problem above was actually because the original code was splitting the date and time into two different parsers. If you use just one parser for both date and time combined you will get the correct date and time in the target locale. So in conclusion the parser is reliable but the way you use it makes a big difference!
SimpleDateFormat simpleDateTimeFormatter
= new SimpleDateFormat("dd/MM/yyyy hh:mm:ss a");
Date getDateTime
= simpleDateTimeFormatter.parse(utcDate + " " + utcTime);
//use above line if you have the date and time as separate strings
simpleDateTimeFormatter.setTimeZone(TimeZone.getDefault());
String getLocalDateTime = simpleDateTimeFormatter.format(getDateTime);
System.out.println("Get local date time: " + getLocalDateTime);
WHY USING TWO SEPARATE PARSERS FOR DATE AND TIME IS UNRELIABLE:
As explained above, it's a bad idea to use two separate parsers for date and time parts. Here's why:
Date getDate = simpleDateFormatter.parse(utcDate);
Date getTime = simpleTimeFormatter.parse(utcTime);
//Time zone changed to local here
String getLocalDate2 = simpleDateTimeFormatter.format(getDate);
String getLocalTime2 = simpleDateTimeFormatter.format(getTime);
System.out.println("Get local date2: " + getLocalDate2);
System.out.println("Get local time2: " + getLocalTime2);
OUTPUT:
Get local date2: 10/11/2012 08:00:00 AM
Get local time2: 01/01/1970 10:35:10 AM
I get the half hour difference because the default date 01/01/1970 is used in the Date variable storing time (second line). When this is converted to local timezone, the error happens as the formatter bases its conversion on the default date 01/01/1970 (where I live, the time difference was +7.5 hours in 1970 - today, it is +8 hours). This is why two separate parsers is not reliable even if you get the right result and you must always use a combined parser that accepts both date and time information.