I am trying to convert Date to Milliseconds without timestamp .
final SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
TimeZone timeZone = TimeZone.getTimeZone("Asia/Kolkata");
sdf.setTimeZone(timeZone);
Date dateObj = sdf.parse(date);
System.out.println ("Milliseconds ="+ dateObj.getTime()) ;
INPUT :
2019-05-08
OUTPUT :
Milliseconds = 1557253800000 // is 2019-05-08T12:00:00 not 2019-05-08T00:00:00
I want to Convert "2019-05-08" to milliseconds of 2019-05-08T00:00:00 ? Any solution for this .
1557253800000 corresponds to 2019-05-07T18:30:00Z. As the timezone Asia/Kolkata is 5:30 hours ahead of UTC this corresponds to 2019-05-08T00:00:00+0530. That is your code is working as expected.
As mentioned by #Lino in the comments with Java 8 the new java.time classes should be used instead of java.util.Date. This would be the corresponding code using the new java.time API:
String str = "2019-05-08";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate date = LocalDate.parse(str, formatter);
ZonedDateTime zonedDateTime = date.atStartOfDay(ZoneId.of("Asia/Kolkata"));
System.out.println(zonedDateTime.toInstant().toEpochMilli()); // will output 1557253800000
zonedDateTime = date.atStartOfDay(ZoneId.of("UTC"));
System.out.println(zonedDateTime.toInstant().toEpochMilli()); // will output 1557273600000
I'm trying to convert the created_utc date from Reddit's json to a Date object, but I keep getting an "Unparceable" error. An example of their dates is: created_utc": 1.43701862E9, which I'm told is a unix timestamp.
From my research this code should convert it:
String date = "1.43701862E9";
java.util.Date time = new java.util.Date((long)date*1000);
but obviously I'm getting an error on multiplying the date by 1000.
This is the code I normally use to convert string dates:
String date = "1.43701862E9";
Calendar cal = Calendar.getInstance(TimeZone.getDefault());
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
format.parse(date);
This should work for you:
public static void main(String[] args) {
String date = "1.43701862E9";
java.util.Date time = new java.util.Date(Double.valueOf(date).longValue()*1000);
System.out.println(time);
}
Output:
Wed Jul 15 23:50:20 EDT 2015
Since you're using scientific notation you can't parse the String using the Long class: Long.parseLong(String s) (Nor can you simply cast a String, as you're trying). Instead, I used the Double.valueOf() method and preserve the Long using .longValue()
The answer by Trobbins is correct but old-school. I lifted that Answer’s math, and used the new java.time classes.
java.time
In Java 8 and later, you can use the new java.time package which supplants the troublesome old java.util.Date/.Calendar classes. (Tutorial)
String input = "1.43701862E9";
long milliSinceEpoch = Double.valueOf( input ).longValue() * 1_000L ;
Instant instant = Instant.ofEpochMilli( milliSinceEpoch ) ;
ZoneId zoneId = ZoneId.of( "America/Montreal" ) ;
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId ) ;
Try to avoid java.util.Date/.Calendar, but if need be you can convert.
java.util.Date date = Date.from( zdt.toInstant() ); // Or… Date.from( instant );
java.util.Calendar calendar = GregorianCalendar.from( zdt );
I want to parse the following string in Java and convert it to a date:
DTSTART;TZID=America/Los_Angeles:20140423T120000
I tried this:
SimpleDateFormat sdf = new SimpleDateFormat("'DTSTART;TZID='Z':'yyyyMMdd'T'hhmmss");
Date start = sdf.parse("DTSTART;TZID=America/Los_Angeles:20140423T120000");
And this:
SimpleDateFormat sdf = new SimpleDateFormat("'DTSTART;TZID='z':'yyyyMMdd'T'hhmmss");
Date start = sdf.parse("DTSTART;TZID=America/Los_Angeles:20140423T120000");
But it still doesn't work. I think the problem is in America/Los_Angeles.
Can you help me please?
Thank you
Try this one using TimeZone.
Note: You have to split your date string before doing this operation.
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd'T'hhmmss");
TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
sdf.setTimeZone(tz);
Date start = sdf.parse("20140423T120000");
In SimpleDateFormat pattern Z represent RFC 822 4-digit time zone
For more info have a look at SimpleDateFormat#timezone.
If you look for a solution how to parse the whole given string in one and only one step then Java 8 offers this option (the pattern symbol V is not supported in SimpleDateFormat):
// V = timezone-id, HH instead of hh for 24-hour-clock, u for proleptic ISO-year
DateTimeFormatter dtf =
DateTimeFormatter.ofPattern("'DTSTART;TZID='VV:uuuuMMdd'T'HHmmss");
ZonedDateTime zdt =
ZonedDateTime.parse("DTSTART;TZID=America/Los_Angeles:20140423T120000", dtf);
Instant instant = zdt.toInstant();
// if you really need the old class java.util.Date
Date jdkDate = Date.from(instant);
Java 8 has a completely new API for date and time. One of the most useful classes in this API is LocalDateTime, for holding a timezone-independent date-with-time value.
There are probably millions of lines of code using the legacy class java.util.Date for this purpose. As such, when interfacing old and new code there will be a need for converting between the two. As there seems to be no direct methods for accomplishing this, how can it be done?
Short answer:
Date in = new Date();
LocalDateTime ldt = LocalDateTime.ofInstant(in.toInstant(), ZoneId.systemDefault());
Date out = Date.from(ldt.atZone(ZoneId.systemDefault()).toInstant());
Explanation:
(based on this question about LocalDate)
Despite its name, java.util.Date represents an instant on the time-line, not a "date". The actual data stored within the object is a long count of milliseconds since 1970-01-01T00:00Z (midnight at the start of 1970 GMT/UTC).
The equivalent class to java.util.Date in JSR-310 is Instant, thus there are convenient methods to provide the conversion to and fro:
Date input = new Date();
Instant instant = input.toInstant();
Date output = Date.from(instant);
A java.util.Date instance has no concept of time-zone. This might seem strange if you call toString() on a java.util.Date, because the toString is relative to a time-zone. However that method actually uses Java's default time-zone on the fly to provide the string. The time-zone is not part of the actual state of java.util.Date.
An Instant also does not contain any information about the time-zone. Thus, to convert from an Instant to a local date-time it is necessary to specify a time-zone. This might be the default zone - ZoneId.systemDefault() - or it might be a time-zone that your application controls, such as a time-zone from user preferences. LocalDateTime has a convenient factory method that takes both the instant and time-zone:
Date in = new Date();
LocalDateTime ldt = LocalDateTime.ofInstant(in.toInstant(), ZoneId.systemDefault());
In reverse, the LocalDateTime the time-zone is specified by calling the atZone(ZoneId) method. The ZonedDateTime can then be converted directly to an Instant:
LocalDateTime ldt = ...
ZonedDateTime zdt = ldt.atZone(ZoneId.systemDefault());
Date output = Date.from(zdt.toInstant());
Note that the conversion from LocalDateTime to ZonedDateTime has the potential to introduce unexpected behaviour. This is because not every local date-time exists due to Daylight Saving Time. In autumn/fall, there is an overlap in the local time-line where the same local date-time occurs twice. In spring, there is a gap, where an hour disappears. See the Javadoc of atZone(ZoneId) for more the definition of what the conversion will do.
Summary, if you round-trip a java.util.Date to a LocalDateTime and back to a java.util.Date you may end up with a different instant due to Daylight Saving Time.
Additional info: There is another difference that will affect very old dates. java.util.Date uses a calendar that changes at October 15, 1582, with dates before that using the Julian calendar instead of the Gregorian one. By contrast, java.time.* uses the ISO calendar system (equivalent to the Gregorian) for all time. In most use cases, the ISO calendar system is what you want, but you may see odd effects when comparing dates before year 1582.
Here is what I came up with ( and like all Date Time conundrums it is probably going to be disproved based on some weird timezone-leapyear-daylight adjustment :D )
Round-tripping: Date <<->> LocalDateTime
Given: Date date = [some date]
(1) LocalDateTime << Instant<< Date
Instant instant = Instant.ofEpochMilli(date.getTime());
LocalDateTime ldt = LocalDateTime.ofInstant(instant, ZoneOffset.UTC);
(2) Date << Instant << LocalDateTime
Instant instant = ldt.toInstant(ZoneOffset.UTC);
Date date = Date.from(instant);
Example:
Given:
Date date = new Date();
System.out.println(date + " long: " + date.getTime());
(1) LocalDateTime << Instant<< Date:
Create Instant from Date:
Instant instant = Instant.ofEpochMilli(date.getTime());
System.out.println("Instant from Date:\n" + instant);
Create Date from Instant (not necessary,but for illustration):
date = Date.from(instant);
System.out.println("Date from Instant:\n" + date + " long: " + date.getTime());
Create LocalDateTime from Instant
LocalDateTime ldt = LocalDateTime.ofInstant(instant, ZoneOffset.UTC);
System.out.println("LocalDateTime from Instant:\n" + ldt);
(2) Date << Instant << LocalDateTime
Create Instant from LocalDateTime:
instant = ldt.toInstant(ZoneOffset.UTC);
System.out.println("Instant from LocalDateTime:\n" + instant);
Create Date from Instant:
date = Date.from(instant);
System.out.println("Date from Instant:\n" + date + " long: " + date.getTime());
The output is:
Fri Nov 01 07:13:04 PDT 2013 long: 1383315184574
Instant from Date:
2013-11-01T14:13:04.574Z
Date from Instant:
Fri Nov 01 07:13:04 PDT 2013 long: 1383315184574
LocalDateTime from Instant:
2013-11-01T14:13:04.574
Instant from LocalDateTime:
2013-11-01T14:13:04.574Z
Date from Instant:
Fri Nov 01 07:13:04 PDT 2013 long: 1383315184574
Much more convenient way if you are sure you need a default timezone :
Date d = java.sql.Timestamp.valueOf( myLocalDateTime );
The fastest way for LocalDateTime -> Date is:
Date.from(ldt.toInstant(ZoneOffset.UTC))
Everything is here : http://blog.progs.be/542/date-to-java-time
The answer with "round-tripping" is not exact : when you do
LocalDateTime ldt = LocalDateTime.ofInstant(instant, ZoneOffset.UTC);
if your system timezone is not UTC/GMT, you change the time !
the following seems to work when converting from new API LocalDateTime into java.util.date:
Date.from(ZonedDateTime.of({time as LocalDateTime}, ZoneId.systemDefault()).toInstant());
the reverse conversion can be (hopefully) achieved similar way...
hope it helps...
If you are on android and using threetenbp you can use DateTimeUtils instead.
ex:
Date date = DateTimeUtils.toDate(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
you can't use Date.from since it's only supported on api 26+
I'm not sure if this is the simplest or best way, or if there are any pitfalls, but it works:
static public LocalDateTime toLdt(Date date) {
GregorianCalendar cal = new GregorianCalendar();
cal.setTime(date);
ZonedDateTime zdt = cal.toZonedDateTime();
return zdt.toLocalDateTime();
}
static public Date fromLdt(LocalDateTime ldt) {
ZonedDateTime zdt = ZonedDateTime.of(ldt, ZoneId.systemDefault());
GregorianCalendar cal = GregorianCalendar.from(zdt);
return cal.getTime();
}
I think below approach will solve the conversion without taking time-zone into consideration.
Please comment if it has any pitfalls.
LocalDateTime datetime //input
public static final DateTimeFormatter yyyyMMddHHmmss_DATE_FORMAT = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String formatDateTime = datetime.format(yyyyMMddHHmmss_DATE_FORMAT);
Date outputDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse(formatDateTime); //output
Can anybody tell me how to convert date to epoch in java.
e.g. 2011-05-01 13:12:20 IST or 2011-05-01 14:11:10 PST to epoch.
I am able to convert using 2011-05-01 13:12:20 format but when I use timezone alongwith it I am not getting correct result.
Construct a SimpleDateFormat with a string pattern that matches the date format you have. The "Date and Time" section and the "Examples" section should give you more than enough help on how to construct your date format string
Then simply do the following to get your date (with the appropriate date format string).
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date date = sdf.parse("15/01/2012");
java.time
Using the java.time classes.
String input = "2011-05-01 13:12:20".replace( " " , "T" );
LocalDateTime ldt = LocalDateTime.parse( input );
ZonedDateTime zdt = ldt.atZone( ZoneId.of( "Asia/Kolkata" ) );
If by “epoch”, you mean a count of whole seconds or milliseconds from the epoch reference date of first moment of 1970 in UTC (often referred to as Unix Time), then interrogate the ZonedDateTime object via an extracted Instant object.
long wholeSecondsSinceEpoch = zdt.toInstant().getEpochSecond();
long millisecondsSinceEpoch = zdt.toInstant().toEpochMilli();