Unparseable Dates with SimpleDateFormat: Specify Locale or Use DateTimeFormatter
Problem:
When using SimpleDateFormat to parse dates, you may encounter the error "java.text.ParseException: Unparseable date," especially when the locale is not specified.
Explanation:
SimpleDateFormat requires a locale to parse dates correctly. If none is specified, it uses the system's default locale, which may not match the format being parsed.
Solution:
- Always specify the locale: Use SimpleDateFormat's constructor overload that accepts a Locale argument. For example:
SimpleDateFormat dtfmt = new SimpleDateFormat("dd MMM yyyy hh:mm a", Locale.ENGLISH);
- Use the modern DateTimeFormatter API:
- DateTimeFormatter is the preferred API for formatting and parsing dates and times.
- It provides greater flexibility and control over formatting, including the ability to specify a locale.
Demo with DateTimeFormatter:
import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; import java.util.Locale; public class Main { public static void main(String[] args) { String strDateTime = "24 Oct 2016 7:31 pm"; DateTimeFormatter dtf = DateTimeFormatter.ofPattern("d MMM uuuu h:m a").withLocale(Locale.ENGLISH); LocalDateTime ldt = LocalDateTime.parse(strDateTime, dtf); System.out.println(ldt); // prints 2016-10-24T19:31 } }
Note:
- The default locale specified by DateTimeFormatter uses the system's current locale.
- Always explicitly specify the locale to avoid potential parsing issues.
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