How to get time and date parts separately from an existing java.util.Date object

Question

I have been trying and trying but I'm pretty surprised as not to be able to find a solution for my simple problem.

I have a date variable which has value like this:

res0: java.util.Date = Mon Jul 15 07:50:59 AET 2019

now I want only the Date part not the time. the functions available in the Date for such are deprecated. and all the solutions I found were using Calendar instance to get today's datetime and convert it into string using SimpleDateFormat.

I don't want a string. I want a Date without the time part and a time without the date part.

You can parse the String as a LocalDateTime, which has methods to extract just the date part as a LocalDate, and just the time part as a LocalTime. — Jordan, Jul 22 '19 at 13:27
FYI, you are using terrible date-time classes that were supplanted years ago by the modern *java.time* classes with the adoption of JSR 310. — Basil Bourque, Jul 22 '19 at 15:08
You really can’t have a `Date` without the time part and one without the date part. A `Date` is always a point in time, nothing more, nothing less. You can of course have a `Date` representing the start of the day in some time zone and another one representing the time of day on the epoch day, Jan 1 1970, in some time zone. It might just be confusing, though. Instead I suggest that you drop the poorly designed `Date` class and use a `LocalDate` for the date and a `LocalTime` for the time of day. That’s exactly what they are for. — Ole V.V., Jul 22 '19 at 20:01

Basil Bourque · Accepted Answer · 2019-07-23T05:50:47.223

tl;dr

myJavaUtilDate
.toInstant()
.atZone(
    ZoneId.of( "Australia/Sydney" )
) 
.toLocalDate()

For time-of-day only, without date and without time zone:

.toLocalTime()

To generate a string, call:

.format(
    DateTimeFormatter
    .ofLocalizedDate( FormatSyle.MEDIUM )
    .withLocale( new Locale( "en" , "AU" ) )
)

Details

Immediately convert your java.util.Date from its legacy class to the modern replacement, Instant.

Instant instant = myJavaUtilDate.toInstant() ;

Both of those classes represent a moment as seen in UTC, that is, an offset of zero hours-minutes-seconds. Adjust into a time zone by which you want to perceive the date.

For any given moment the time-of-day and the date both vary by time zone around the globe. Noon in Paris is not noon in Montréal. And a new day dawns earlier in the east than in the west. You must get very clear on this to do proper date-time handling. One moment in nature can be viewed in many ways through human-created notions of time zones.

Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter pseudo-zones such as AET, EST, or IST as they are not true time zones, not standardized, and not even unique(!).

ZoneId z = ZoneId.of( "Australia/Sydney" ) ;

Apply to the Instant to get a ZonedDateTime. Both represent the same simultaneous moment, but are viewed with a different wall-clock time.

ZonedDateTime zdt = instant.atZone( z ) ;

Extract the date-only portion.

LocalDate ld = zdt.toLocalDate() ;

Extract the time-of-day portion.

LocalTime lt = zdt.toLocalTime() ;

Put them back together again.

ZonedDateTime zdt = ZonedDateTime.of( ld , lt , z ) ;

If you need a java.util.Date again to interoperate with old code not yet updated to java.time, convert.

Date d = Date.from( zdt.toInstant() ) ;

nice explanation! thanks a lot. I'm relatively new to Scala/Java world. hence I'm bound to make mistakes :) — Simple Fellow, Jul 23 '19 at 07:05

pme · Answer 2 · 2019-07-22T15:05:08.130

2

You can use LocalDate

val input = new Date() // your date
val date = input.toInstant().atZone(ZoneId.of("Europe/Paris")).toLocalDate()

Here is a good answer: https://stackoverflow.com/a/21242111/2750966

edited Jul 22 '19 at 15:05

answered Jul 22 '19 at 13:27

pme

14,156
3
52
95

1

“AET” is a pseudo-zone. A real time zone has a name in the format of `Continent/Region`. – Basil Bourque Jul 22 '19 at 14:52

Mysterious Wolf · Answer 3 · 2019-07-22T13:44:44.670

1

You could use date formatter to turn it into String and parse it back to Date.

For example:

Date yourDate = ...;
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
Date date = dateFormat.parse(dateFormat.format(yourDate));

The new date object now only has the date part, with the time part being filled with zeroes. For a numeric solution with the same result, check out this answer. Alternatively, if you don't want the time part at all, this answer should suit you better.

edited Jul 22 '19 at 13:44

answered Jul 22 '19 at 13:25

Mysterious Wolf

373
1
5
22

the question is How?.. I'm not an expert of Java world – Simple Fellow Jul 22 '19 at 13:27
I added an example to my answer – Mysterious Wolf Jul 22 '19 at 13:33
yes but ... I don't get it. you convert the date to string and then again to a date. I mean it gets the job done but feels like a somersault – Simple Fellow Jul 22 '19 at 13:35
1

It's just one way of doing it. It may be an extra step, but it's a quick solution. As always there are other ways of doing it like stated in the other answers. – Mysterious Wolf Jul 22 '19 at 13:44
1

These terrible date-time classes were supplanted years ago by the modern *java.time* classes with the adoption of JSR 310. – Basil Bourque Jul 22 '19 at 14:51

MilanRegmi · Answer 4 · 2019-07-23T13:32:18.787

We can do this using the date formatter, you can try the following code.

object DateFormatter extends App {
  val sdf = new SimpleDateFormat("EEEE MMMM dd, HH:mm:ss:SSS Z yyyy", Locale.ENGLISH)
  val date = new Date()
  val nowDate = sdf.format(date)
  println(nowDate)
  // It prints date in this format Monday July 22, 23:40:07:987 +0545 2019

  // Lets print the date in the format you have provided in your question
  val parsedDate = sdf.parse(nowDate)
  println(parsedDate)

  // Now, we have same date format as yours

  // Now we have to remove the time and keep the date part only, for this we can do this
  val newDateFormat = new SimpleDateFormat("yyyy-MM-dd")
  val dateOnly = newDateFormat.format(parsedDate)
  println(dateOnly)

  //Printing time only
  val timeFormatter = new SimpleDateFormat("HH:mm:ss")
  val timeOnly = timeFormatter.format(parsedDate)
  println(timeOnly)

  }

Output:

nowDate: Tuesday July 23, 07:08:05:857 +0545 2019
parsedDate: Tue Jul 23 07:08:05 NPT 2019
dateOnly: 2019-07-23
timeOnly: 07:08:05

Update

val dateNotInString = newDateFormat.parse(dateOnly)
  println(dateNotInString)

Output of Update:

dateNotInString: Tue Jul 23 00:00:00 NPT 2019

Here, you can see that dateNotInString is a date object and it does not contain any time related info. Similarly, time only info can be extracted.

Second Update

We can’t have a Date without the time part and without the date part using the SimpleDateFormat with type not String but we can convert it into LocaleDate and LocaleTime.

import java.time.Instant

  val instantTime = Instant.ofEpochMilli(parsedDate.getTime)

  import java.time.LocalDateTime
  import java.time.LocalTime
  import java.time.ZoneId

  val res = LocalDateTime.ofInstant(instantTime, ZoneId.systemDefault).toLocalTime
  println("localeTime " + res)

  val res1 = LocalDateTime.ofInstant(parsedDate.toInstant,ZoneId.systemDefault).toLocalDate
  println("localeDate " + res1)

Output of the second Update

localeTime: 18:11:30.850
localeDate: 2019-07-23

It's type is LocaleTime and LocaleDate respectively now.

thanks a lot. however I think you missed the last line of the problem _I don't want a string. I want a Date without the time part and a time without the date part._ If you can alter your solution a bit? — Simple Fellow, Jul 23 '19 at 05:23
I don't think that is important. Check the second update please. — MilanRegmi, Jul 23 '19 at 12:37

score 0 · Answer 5 · edited Jul 22 '19 at 14:29

    Date date = new Date(res0.getTime() - (res0.getTime() % 86400000));
    System.out.println(date);

Now you can use the date formatter as is with your res0 date and it will print the date only. But what I tried to do is remove the time part basically 86400000 is the number of milliseconds per day and getTime return the number of milliseconds passed since January 1, 1970, 00:00:00 GMT. So basically this is equivalent to the date at time 00:00.00 of each day. I don't know if this is what you want because Date doesn't hold 2 separate things like date and time it just has a single long.

How to get time and date parts separately from an existing java.util.Date object

5 Answers5

tl;dr

Details