How to get the same output of departed Date.parse() in groovy?-CodePudding

I have an application that runs the old version of the spring application. The application has the function to create date objects using Date.parse as follows

Date getCstTimeZoneDateNow() {
  String dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
  def zonedDateString = new Date().format(dateFormat, TimeZone.getTimeZone('CST'))
  Date date = Date.parse(dateFormat, zonedDateString)
  return date // Tue Oct 18 20:36:12 EDT 2022 (in Date)
}

However, the code above is deprecated. I need to produce the same result. I read other posts and it seems like Calender or SimpleDateFormatter is preferred. And I thought SimpleDateFormatter has more capabilities.

This post helped me understand more about what is going on in the following code SimpleDateFormat parse loses timezone

Date getCstTimeZoneDateNow() {
  Date now = new Date()
  String pattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"

  SimpleDateFormat sdf = new SimpleDateFormat()
  sdf.setTimeZone(TimeZone.getTimeZone('CST'))

  // cstDateTime prints times in cst
  String cstDateTime = sdf.format(now)  // 2022-10-18T20:36:12.088Z (in String)
  // JVM current time
  Date date = sdf.parse(cstDateTime) // Tue Oct 18 21:36:12 EDT 2022 (in Date)

  return date 
}

Here my goal is to return the date object that is in the format of Tue Oct 18 20:36:12 EDT 2022 The format is good. However, like the post says, when I do sdf.parse(), it prints in JVM time. This means, the format is good but the time zone is off. How can I get the exact same result as before? It does not have to use SimpleDateFormatter. Could be anything.

Thank you so much for reading and for your time.

CodePudding user response：

Perhaps the line where you assign the format with the time-zone should be changed to make it work:

sdf.setTimeZone(TimeZone.getTimeZone('CST'))

Also the pattern seems to be obsolete, as I can't see it is used anywhere.

Try to check the output before returning 'date':

printf("cstData2: %s%n", sdf.format(date))

CodePudding user response：

Perhaps it is a logical error. It depends on the date, which time-difference is currently seen.

In this example, I try to demonstrate my output when the JVM timezone is EDT, for me, this output looks reasonable:

Date now = new Date()
printf("date: %s%n", now);
SimpleDateFormat sdf = new SimpleDateFormat()
sdf.setTimeZone(TimeZone.getTimeZone('CST'))
String formatted = sdf.format(now) 
printf("formatted: %s%n", formatted)
Date date = sdf.parse(formatted)
String parsed = sdf.format(date)
printf("parsed: %s%n", parsed)
printf("date: %s%n", date);
return date

Output:

date: Thu Oct 20 02:27:53 EDT 2022
formatted: 10/20/22 1:27 AM
parsed: 10/20/22 1:27 AM
date: Thu Oct 20 02:27:00 EDT 2022

Hint: This are the actual resolved offsets for CST and EDT:

printf("offset EDT %s%n", TimeZone.default.getOffset(new Date().time)/(60*60*1000))
printf("offset CST %s%n", TimeZone.getTimeZone('CST').getOffset(new Date().time)/(60*60*1000))

Output:

offset EDT -4
offset CST -5