Kotlin Android / Java 字符串日期时间格式，API21

Question

I want convert string datetime to formatted string. eg "2018-12-14T09:55:00" to "14.12.2018 09:55" as String => Textview.text

how can I do this with kotlin or java for android?

Answer 1

Parse it to LocalDateTime then format it:

LocalDateTime localDateTime = LocalDateTime.parse("2018-12-14T09:55:00");
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm");
String output = formatter.format(localDateTime);

If this does not work with api21, you can use:

SimpleDateFormat parser = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
SimpleDateFormat formatter = new SimpleDateFormat("dd.MM.yyyy HH:mm");
String output = formatter.format(parser.parse("2018-12-14T09:55:00"));

or import ThreeTenABP.

Answer 2

Kotlin API levels 26 or greater:

val parsedDate = LocalDateTime.parse("2018-12-14T09:55:00", DateTimeFormatter.ISO_DATE_TIME)
val formattedDate = parsedDate.format(DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm"))

Below API levels 26:

val parser =  SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss")
val formatter = SimpleDateFormat("dd.MM.yyyy HH:mm")
val formattedDate = formatter.format(parser.parse("2018-12-14T09:55:00"))

Answer 3

If you have a date-time that represents a value in a specific time zone but the zone is not encoded in the date-time string itself (eg, "2020-01-29T09:14:32.000Z") and you need to display this in the time zone you have (eg, CDT)

val parsed = ZonedDateTime.parse("2020-01-29T09:14:32.000Z", DateTimeFormatter.ISO_DATE_TIME).withZoneSameInstant(ZoneId.of("CDT"))

That parsed ZoneDateTime will reflect the time zone given. For example, this date would be something like 28 Jan 2020 at 8:32am.

Answer 4

In kotlin u can do this way to format string to date :-

val simpleDateFormat = SimpleDateFormat("yyyy/MM/dd HH:mm:ss",Locale.getDefault())
val date = SimpleDateFormat("yyyy/MM/dd", Locale.getDefault()).format(simpleDateFormat.parse("01-02-2022 14:23:05")!!)

Should import java.text.SimpleDateFormat For SimpleDateFormat Class to work on api 21

Answer 5

Here is Kotlin One Liner,It will return empty string if input date cannot be parsed.

fun String.getDateInAnotherFormat(inputFormat: String,outputFormat: String):String = SimpleDateFormat(inputFormat, Locale.getDefault()).parse(this)?.let { SimpleDateFormat(outputFormat,Locale.getDefault()).format(it) }?:""

Usage:

var dateStr = "2000-12-08"
dateStr.getDateInAnotherFormat("yyyy-MM-dd","MMM dd YYYY")