How to parse an ISO date with LocalDateTime.parse(...)

Question

I want to parse a date string like 2011-11-30 like this:

LocalDateTime.parse("2011-11-30", DateTimeFormatter.ISO_LOCAL_DATE)

But I get the following exception:

java.time.format.DateTimeParseException: Text '2011-11-30' could not be parsed:
Unable to obtain LocalDateTime from TemporalAccessor

If I pass a date and time string everything works as expected:

LocalDateTime.parse("2011-11-30T23:59:59", DateTimeFormatter.ISO_LOCAL_DATE_TIME)

How can I parse a date like 2011-11-30 to a LocalDateTime (with a default time)?

Derwin

Well, use LocalDate.parse(), and then change it to a LocalDateTime by specifying which time you want. – Cotopaxi

Answer 1

As @JB Nizet suggested, the following works

LocalDate localDate = LocalDate.parse("2011-11-30", DateTimeFormatter.ISO_LOCAL_DATE);
LocalDateTime localDateTime = localDate.atTime(23, 59, 59);
System.out.println(localDateTime); // 2011-11-30T23:59:59

How can I parse a date like 2011-11-30 to a LocalDateTime (with a default time)?

1. Parse it first in a LocalDate
2. Use LocalDateTime atTime() method to set your default time

Note: Use of DateTimeFormatter.ISO_LOCAL_DATE is superfluous for parse(), see API LocalDate#parse()

Homoeroticism

Answer 2

The sample below use some magic numbers, wich should be avoid (What is a magic number, and why is it bad?).

Instead of using the method atTime(hour, minute, second),

    LocalDate localDate = LocalDate.parse("2011-11-30", DateTimeFormatter.ISO_LOCAL_DATE);
    LocalDateTime localDateTime = localDate.atTime(23, 59, 59);

you can use the LocalTime constants, such as LocalTime.MAX, (23:59:59), LocalTime.MIN (00:00:00), LocalTime.MIDNIGHT (23:59:59) or LocalTime.NOON (12:00:00)

    LocalDate localDate = LocalDate.parse("2011-11-30", DateTimeFormatter.ISO_LOCAL_DATE);
    LocalDateTime localDateTime = LocalDateTime.of(localDate, LocalTime.MIN);

It is better for maintainability and cross-reference.

Openandshut

Thank you for this code snippet, which might provide some limited short-term help. A proper explanation would greatly improve its long-term value by showing why this is a good solution to the problem, and would make it more useful to future readers with other, similar questions. Please edit your answer to add some explanation, including the assumptions you've made. – Entertainment

Answer 3

Why I've written this answer despite existing answers

Unfortunately, all of the existing answers are only partially correct. They lack the following important aspects of the modern date-time API:

1. Using ISO format while parsing a date string
2. How to apply the current time to an instance of LocalDateTime to get a new instance of LocalDateTime with the current time

Question posted by OP:

How can I parse a date like 2011-11-30 to a LocalDateTime (with a default time)?

Answer

There are two problems with your approach:

1. Since you are parsing a date string, you should have used LocalDate#parse instead of LocalDateTime#parse.

2. Since your date string is already in the ISO pattern, you need not specify this pattern using DateTimeFormatter explicitly as LocalDate.parse uses this pattern by default.

   Apart from these two problems, you will need to use LocalDateTime#with to apply the current time to an instance of LocalDateTime to get a new instance of LocalDateTime with the current time.

   import java.time.LocalDate;
   import java.time.LocalDateTime;
   import java.time.LocalTime;
   
   public class Main {
       public static void main(String[] args) {
           // No need to specify DateTimeFormatter as the string is already in ISO format
           LocalDate date = LocalDate.parse("2011-11-30");
           System.out.println(date);
   
           // Get LocalDateTime from LocalDate
           LocalDateTime ldt = date
                               .atStartOfDay()         //Convert to LocalDateTime with 00:00
                               .with(LocalTime.now()); //Adjust to current time
   
           System.out.println(ldt);
       }
   }
   

   Output:

   2011-11-30
   2011-11-30T11:53:39.103150
   

Note: Learn more about the modern date-time API from Trail: Date Time.

Extradite