Develop Reference

How to format string to date in Android

In my application I one string such as 2023-2-14 and I want convert this to 2023-02-14.
I write below codes:
val format = SimpleDateFormat("yyyy-MM-dd")
val date: Date = format.parse(startDateStr)
Log.e("dateLog",""+date)
But in logcat show me this : Wed Feb 15 00:00:00 GMT+03:30 2023
Why? I used this format : yyyy-MM-dd.
Why not used this format?

you are just parsing date, without a time, thus date object have set 00 for hour, day etc. now use format method for converting old String to new one
val formatAs = "yyyy-MM-dd"
var format = SimpleDateFormat(formatAs)
val date: Date = format.parse(startDateStr)
Log.e("dateLog","date:"+date)
String dateAsStringFormatted = format.format(date);
Log.e("dateLog","dateAsStringFormatted:"+dateAsStringFormatted)
some other answers in HERE

How to Convert "2021-05-14T13:42:48.000Z" string to Date Object?

I am trying to convert "2021-05-14T13:42:48.000Z" string to Date Object.
I have tried this:
DateFormat dateFormat = new SimpleDateFormat("YYYY-MM-DDHH:MM:SS");
And also this, which i saw on stackoverflow only:-
DateFormat dateFormat = new SimpleDateFormat("YYYY-MM-DD'T'HH:MM:SS'A'");
But none of it worked.
How can i convert this string to my date object?

Assuming your date string always represents a UTC time (with the 'Z'), you can use format string:
yyyy-MM-dd'T'HH:mm:ss.SSSZ
but you'll first need to replace the Z in your date string with the fixed timezone "+0000", as in "2021-05-14T13:42:48.000+0000".
Try this:
String myDateString = "2021-05-14T13:42:48.000Z"
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ", Locale.US);
Date myDate = dateFormat.parse (myDateString.replace("Z","+0000"));
This will return a date correctly adjusted for your current timezone, in my case 9:42:48am EDT.
There is a more detailed discussion at Converting ISO 8601-compliant String to java.util.Date which you may find useful.

You have used the date-time format incorrectly. It's important to note that the date-time formats have different meanings between capitalized and small letters.
For example: Capital MM means months, whereas small mm means minutes.
To know more about the date formats, you can refer this:
https://cheatography.com/pezmat/cheat-sheets/date-time-formats/pdf/
or this:
https://devhints.io/datetime
And the answer for your case is:
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");

Please do not use SimpleDateFormat or even java.date. All these classes are deprecated.
Instead, rely on the Android available java.time package.
In short:
val source = "2021-05-14T13:42:48.000Z"
val parsed = ZonedDateTime.parse(source)
This will correctly parse the timezone (Z for Zulu/UTC/GMT).
You can verify this, by simply converting the parsed Zoned date time into, for example, Europe/Amsterdam time (which is +2).
val source = "2021-05-14T13:42:48.000Z"
val parsed = ZonedDateTime.parse(source)
parsed.toString() // prints: 2021-05-14T13:42:48Z
parsed.zone // prints: "Z"
ZoneId.of(parsed.zone.id) // returns the ZoneOffset "Z" (correct)
// Convert to Amsterdam Time
val amsterdamDateTime = parsed.withZoneSameInstant(ZoneId.of("Europe/Amsterdam"))
amsterdamDateTime.toString() // prints: 2021-05-14T15:42:48+02:00[Europe/Amsterdam] (2 hours ahead of the Zulu time, also correct).
parsed.format(DateTimeFormatter.ISO_DATE_TIME).toString() // Prints: 2021-05-14T13:42:48Z (correct)
So as you can see, these classes do the right thing (most of the time).
I suggest you use them.

Convert string into LocalDateTime

I have the following String:
18/07/2019 16:20
I try to convert this string into LocalDateTime with the following code:
val stringDate = expiration_button.text.toString()
val date = LocalDateTime.parse(stringDate, DateTimeFormatter.ofPattern("dd/MM/yyyy hh:mm")).toString()
java.time.format.DateTimeParseException: Text '18/07/2019 04:30:00'
could not be parsed: Unable to obtain LocalDateTime from
TemporalAccessor
What I'm missing?

I think this will answer your question:
val stringDate = expiration_button.text.toString()
val formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy hh:mm");
val dt = LocalDate.parse(stringDate, formatter);
Edit 1:
It's probably crashing because you are using a 12hr Hour, instead of a 24hr pattern.
Changing the hour to 24hr pattern by using a capital H should fix it:
val dateTime = LocalDateTime.parse(stringDate, DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm"));

Use below to convert the time from String to LocalDateTime, but make sure you are getting the time in String form.
String str = "2016-03-04 11:30";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
LocalDateTime dateTime = LocalDateTime.parse(str, formatter);
Btw, If your String contains seconds as well like "2016-03-04 11:30: 40", then you can change your date time format to yyyy-MM-dd HH:mm:ss" as shown below:
String str = "2016-03-04 11:30: 40";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
LocalDateTime dateTime = LocalDateTime.parse(str, formatter);

Change your datetime format to "dd/MM/yyyy hh:mm a" and provide a string date with additional AM/PM information, e.g. val stringDate = "18/07/2019 04:20 PM" or just use the 24 hour format "dd/MM/yyyy HH:mm".

You may try using "-" instead of "/" on the date.

Date parsing. How do I parse this date format? [duplicate]

This question already has answers here:
Convert JSON date format
(5 answers)
Closed 5 years ago.
How do I parse this date format:
"/Date(1514728800000+0300)/"
I don't know what the meaning of this number is, or that of the + sign.

Partial answer: the number is the epoch time.
This is the amount of seconds since Jan 1, 1970, UTC.
You can pass this value to the constructor of java.util.Date, which will get you a Date object with the right value.
The +0300 is unclear, perhaps a reference to a different timezone.

Im not sure about the +0300, but you can convert a epoch time to Date with the following function:
Date date = new Date(Long.parseLong(myDateToParse.replaceAll("[^\\d-]", "")));
SimpleDateFormat sdf = new SimpleDateFormat("yyyy.MM.dd HH:mm:ss", Locale.DEFAULT);

Here is the code that parses this assuming you have unixtimestamp_zoneoffset
String inputStr = "1514728800000+0300";
String[] splitStr = inputStr.split("[+-]");
String offsetSign = inputStr.indexOf("+")>0 ? "+" : "-";
ZonedDateTime captureTime = Instant.ofEpochMilli(Long.valueOf(splitStr[0])).atZone(ZoneOffset.of(offsetSign+splitStr[1]));
The value returned is 2017-12-31T17:00+03:00

ThreeTenABP not parsing date

I am trying to convert ISO 8601 time into something human readable and in the local timezone of the Android device.
String date = "2016-09-24T06:24:01Z";
LocalDate test = LocalDate.parse(date, ISO_INSTANT);
But it returns:
method threw 'org.threeten.bp.format.DateTimeParseException' exception
From reading http://www.threeten.org/threetenbp/apidocs/org/threeten/bp/format/DateTimeFormatter.html#ISO_INSTANT it seems like what I'm doing should be possible.
What am I doing wrong?
Edit
Expanded exception error:
Unable to obtain LocalDate from TemporalAccessor: DateTimeBuilder[fields={MilliOfSecond=0, NanoOfSecond=0, InstantSeconds=1474698241, MicroOfSecond=0}, ISO, null, null, null], type org.threeten.bp.format.DateTimeBuilder
Edit 2
The solution is in the answer below. For anyone that stumbles across this, if you want to specify a custom output format you can use:
String format = "MMMM dd, yyyy \'at\' HH:mm a";
String dateString = DateTimeFormatter.ofPattern(format).withZone(ZoneId.systemDefault()).format(instant);

#alex answer is correct. Here is a working example.
Instant represents a point in time. To convert to any other local types you will need timezone.
String date = "2016-09-24T06:24:01Z";
This date string is parsed using the DateTimeFormatter#ISO_INSTANT internally.
Instant instant = Instant.parse(date);
From here you can convert to other local types just using timezone ( defaulting to system time zone )
LocalDateTime localDateTime = instant.atZone(ZoneId.systemDefault()).toLocalDateTime();
LocalDate localDate = instant.atZone(ZoneId.systemDefault()).toLocalDate();
LocalTime localTime = instant.atZone(ZoneId.systemDefault()).toLocalTime();
Alternatively, you can use static method to get to local date time and then to local date and time.
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
LocalDate localDate = localDateTime.toLocalDate();
LocalTime localTime = localDateTime.toLocalTime();

You need to use Instant.parse().
This will give you an Instant that you can combine with a time zone to create a LocalDate.

In Kotlin:
Converts to LocalDateTime directly based on your local time zone::
val instant: Instant = Instant.parse("2020-04-21T02:22:04Z")
val localDateTime = instant.atZone(ZoneId.systemDefault()).toLocalDateTime()
Converts to Date and time separately based on your local time zone:
val localDate: LocalDate = instant.atZone(ZoneId.systemDefault()).toLocalDate()
val localTime: LocalTime = instant.atZone(ZoneId.systemDefault()).toLocalTime()