1. Introduction
When dealing with date/time in Java, DateTimeParseException is an exception you’ll probably encounter. In this article, you’ll learn how to fix this exception. You’ll also learn some best practices for avoiding the DateTimeParseException.
2. What Java Says about DateTimeParseException
According to the Javadoc, a DateTimeParseException is thrown to indicate problems when parsing datetime objects.
3. How to Reproduce
3.1. Using the LocalDate Class
Let’s consider the following code which attempts to create a LocalDate with an invalid String value:
String invalidDateFormat = "01/05/2024";// Non ISO-8601 date format
LocalDate date = LocalDate.parse(invalidDateFormat);// DateTimeParseException
Running the above code snippet will print the following to the console:
Exception in thread "main" java.time.format.DateTimeParseException: Text '01/05/2024' could not be parsed at index 0
at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2052)
at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1954)
at java.base/java.time.LocalDate.parse(LocalDate.java:430)
at java.base/java.time.LocalDate.parse(LocalDate.java:415)
at Scratch.main(scratch.java:14)
By default, Java uses the standard ISO datetime format.
String validDateFormat = "2024-05-01";// ISO-8601 date format
LocalDate date = LocalDate.parse(validDateFormat);// No DateTimeParseException
3.2. Using the LocalTime Class
The code below is attempting to parse a LocalTime with an invalid hour value:
String invalidTimeFormat = "04:00 PM";// Non ISO-8601 date format
LocalTime date = LocalTime.parse(invalidTimeFormat);// DateTimeParseException
Output:
Exception in thread "main" java.time.format.DateTimeParseException: Text '04:00 PM' could not be parsed at index 0
at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2052)
at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1954)
at java.base/java.time.LocalDate.parse(LocalDate.java:430)
at java.base/java.time.LocalDate.parse(LocalDate.java:415)
at Scratch.main(scratch.java:8)
Like LocalDate, LocaleTime uses the standard ISO format, a 24-hour time format.
String validTimeFormat = "16:00";// ISO-8601 date format
LocalTime date = LocalTime.parse(validTimeFormat);// No DateTimeParseException
3.3. Using the DateTimeFormatter Class
A common source of DateTimeParseException is when you create a DateTimeFormatter without explicitly passing a Locale object.
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss a");
LocalDateTime date = LocalDateTime.parse("2024-05-29 03:05:00 PM",formatter);//DateTimeParseException if run on a system with a Locale that uses “AM/PM” symbols instead of “am/pm” (e.g. India)
If you run the above code on a system with a Locale that uses “am/pm” symbols instead of “AM/PM”, a DateTimeParseException is thrown. This will happen for example if you run the code in India.
Exception in thread "main" java.time.format.DateTimeParseException: Text '2024-05-29 03:05:00 PM' could not be parsed at index 20
at java.base/java.time.format.DateTimeFormatter.parseResolved0(DateTimeFormatter.java:2052)
at java.base/java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1954)
at java.base/java.time.LocalDateTime.parse(LocalDateTime.java:494)
at Scratch.main(scratch.java:11)
You must explicitly pass a Locale to the DateTimeFormatter to fix this error.
Locale locale = new Locale("en");
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss a", locale);
LocalDateTime date = LocalDateTime.parse("2024-05-29 03:05:00 PM",formatter);//No DateTimeFormatter
4. Best Practices to Avoid DateTimeParseException
4.1. Always pass a Locale when constructing a DateTimeFormatter
You should always provide an appropriate Locale object to the DateTimeFormatter during its creation. This will prevent unexpected behavior if your code is run on a different system.
Locale locale = new Locale("in");//India
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm:ss a", locale);
LocalDateTime date = LocalDateTime.parse("2024-05-29 03:05:00 pm",formatter);//No DateTimeFormatter
4.2. Use Suitable Data Types
Always make sure you choose the proper data type according to your needs:
- Use LocalDate for date-only values: “2024-05-25”
- Use LocalTime for time-only values: “15:30”
- Use LocalDateTime for combined date and time values: “2024-05-25T15:30”
- Use ZonedDateTime or OffsetDateTime for date and time values with time zone or offset: “2024-05-25T15:30:15.962090600+02:00[Europe/Paris]”
5. Conclusion
In this brief tutorial, you learned about the DateTimeParseException and how to fix it.
You can find the complete code of this article here in GitHub
