Date and Time in Kotlin - datetime

Question

I am new to kotlin. And I got a problem.
I have this code:
val sdf = SimpleDateFormat("dd.MM.yyyy")
val currentDate = sdf.format(Date())
println(currentDate)
val stringDate = "12.03.2015"
val dateFormatter = DateTimeFormatter.ofPattern("dd.MM.yyyy", Locale.ENGLISH)
val millisecondsSinceEpoch = LocalDate.parse(stringDate, dateFormatter)
.atStartOfDay(ZoneOffset.UTC)
.toInstant()
.toEpochMilli()
println(millisecondsSinceEpoch)
val time = currentDate - millisecondsSinceEpoch
val Datee = sdf.format(time)
println(Datee)
But on the line:
val time = currentDate - millisecondsSinceEpoch
val Datee = sdf.format(time)
println(Datee)
I get the error:
java.lang.IllegalArgumentException: Cannot format given Object as a Date
Please help me how you can fix this. I need to subtract the current date from the date that is in string.
UPDATE:
How to subtract one date from another correctly and get the difference in days?

Answer 1

I suggest you switch from the outdated java.util date/time API to the modern date/time API. Given below is the Java code for your requirement and I hope you should be able to convert the same into Kotlin. However, if you face any issue, I can convert the same into Kotlin code for you.
import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Period;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
// Define format
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy", Locale.ENGLISH);
// Given date-time
ZonedDateTime givenDateTime = LocalDateTime.of(LocalDate.parse("12.03.2015", formatter), LocalTime.of(0, 0))
.atZone(ZoneId.of("Etc/UTC"));
// Now
ZonedDateTime zdtNow = ZonedDateTime.now(ZoneId.of("Etc/UTC"));
// Period between the two dates
Period period = Period.between(givenDateTime.toLocalDate(), zdtNow.toLocalDate());
// Given date-time with current year, month and day
ZonedDateTime adjusted = givenDateTime.with(LocalDate.now(ZoneId.of("Etc/UTC")));
// Duration between the two times
Duration duration = Duration.between(adjusted, zdtNow);
// Display each part of the period and duration
System.out.printf("%d years %d month %d days %d hours %d minutes %d seconds %d nanoseconds", period.getYears(),
period.getMonths(), period.getDays(), duration.toHoursPart(), duration.toMinutesPart(),
duration.toSecondsPart(), duration.toNanosPart());
}
}
Output:
5 years 4 month 7 days 19 hours 30 minutes 37 seconds 507058000 nanoseconds
Using OffsetDateTime:
import java.time.Duration;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.OffsetDateTime;
import java.time.Period;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
// Define format
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd.MM.yyyy", Locale.ENGLISH);
// Given date-time
OffsetDateTime givenDateTime = LocalDateTime.of(LocalDate.parse("12.03.2015", formatter), LocalTime.of(0, 0))
.atOffset(ZoneOffset.UTC);
// Now
OffsetDateTime odtNow = OffsetDateTime.now(ZoneOffset.UTC);
// Period between the two dates
Period period = Period.between(givenDateTime.toLocalDate(), odtNow.toLocalDate());
// Given date-time with current year, month and day
OffsetDateTime adjusted = givenDateTime.with(LocalDate.now(ZoneOffset.UTC));
// Duration between the two times
Duration duration = Duration.between(adjusted, odtNow);
// Display each part of the period and duration
System.out.printf("%d years %d month %d days %d hours %d minutes %d seconds %d nanoseconds", period.getYears(),
period.getMonths(), period.getDays(), duration.toHoursPart(), duration.toMinutesPart(),
duration.toSecondsPart(), duration.toNanosPart());
}
}

Answer 2

Following is the corrected version of your initial program. However as others pointed out it is advisable to use new java Time API.
There is nice article highlighting problem with old Java Date and Calendar API
https://programminghints.com/2017/05/still-using-java-util-date-dont/
import java.util.Date
import java.util.Locale
import java.time.Instant
import java.time.LocalDateTime
import java.time.LocalDate
import java.time.ZoneOffset
import java.text.SimpleDateFormat
import java.time.format.DateTimeFormatter
fun main(args: Array<String>) {
val sdf = SimpleDateFormat("dd.MM.yyyy")
val currentDate = Date()
val currentFormattedDate = sdf.format(currentDate)
println(currentFormattedDate)
val now = currentDate.getTime();
val stringDate = "12.03.2015"
val dateFormatter = DateTimeFormatter.ofPattern("dd.MM.yyyy", Locale.ENGLISH)
val millisecondsSinceEpoch = LocalDate.parse(stringDate, dateFormatter)
.atStartOfDay(ZoneOffset.UTC)
.toInstant()
.toEpochMilli()
println(millisecondsSinceEpoch)
val time = now - millisecondsSinceEpoch
val Datee = sdf.format(time)
println(Datee)
}

Answer 3

Thanks everyone. But I decided to do this. And it seems like everything works)
fun daysString(dataend: String):String{
val dateFormat = SimpleDateFormat("dd.MM.yyyy")
val endDate = dateFormat.parse(dataend)
val currentDate = Date()
val time = endDate.time - currentDate.time
val days = time / 1000 / 3600 / 24
val strtoday = days.toString()
return strtoday
}
Now in the code I am using:
val data_end = "10.10.2020"
daysString(data_end)
and I get strtoday

Answer 4

Get your required Date and then can do this:
val sdf = SimpleDateFormat("dd/MM/yyyy",Locale.ENGLISH)
val theDate = sdf.parse(selectedDate)
val selectedDate = theDate!!.time/86400000 //.time gives milliseconds
val currentDate = sdf.parse(sdf.format(System.currentTimeMillis()))
val currentDate = currentDate!!.time/86400000 //86400000 milliseconds in a day
val diff = currentDate - selectedDate
println(diffInMinutes.toString()) //set it to any view or use as needed