Why Does SimpleDateFormat.parse Yield an Unexpected Output Format?

SimpleDateFormatter.parse Giving Unexpected Output Format

In your code, you've encountered a discrepancy where SimpleDateFormatter.format and SimpleDateFormatter.parse produce different output formats. Let's delve into the reasons behind this behavior.

The SimpleDateFormatter class requires both date formatting and time zone information to manipulate dates correctly. In your case, the format you've specified is "dd/MM/yyyy hh:mm:ss a" (e.g., 23/05/2018 03:30:00 PM). However, when you parse the formatted date back using the same format, it recognizes the IST (Indian Standard Time) time zone due to the "a" in the format, which represents the AM/PM designation.

This means that SimpleDateFormatter.parse interprets the date with the IST time zone in place, resulting in the timestamp you observed: "Wed May 23 15:30:00 IST 2018." This format is different from the one you originally specified because it includes the time zone information.

To resolve this issue, consider the following solutions:

• Use java.time's LocalDateTime: As suggested in the accepted answer, utilizing the java.time API's LocalDateTime provides a cleaner and more modern approach. This object encapsulates date and time information without time zone bias. You can convert an epoch timestamp into a LocalDateTime and directly insert it into your MySQL database without facing parsing issues.
• Set the Time Zone Explicitly: Alternatively, if you wish to use SimpleDateFormatter, ensure that you explicitly set the time zone before applying parse. By specifying the time zone upfront, you can control the interpretation of date and time values.

In summary, the discrepancy between SimpleDateFormatter.format and SimpleDateFormatter.parse arises due to time zone considerations. By leveraging the java.time API or explicitly managing time zones in SimpleDateFormatter, you can avoid these formatting inconsistencies and ensure consistent date handling.

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