The game doesn't recognise the ISO 8601 date format

Is this still a concern in the latest Minecraft version 14w08a? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Is this still a concern in the current Minecraft version 1.7.9 / Launcher version 1.3.11 or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Screen shot of World Selection screen showing the undesired date format.
(Minecraft 1.8.1, any Java version)

Mac OS Language & Region part of System Preferences. Circled are the desired date/time formats which result from the OS settings chosen by the user. The Minecraft World Selection screen does not follow these settings.

For completeness, here is a report that follows the guidelines.

Report:
When starting Minecraft, the World selection screen shows the dates and times when each of the worlds was last saved. These dates and times are in the wrong format.

What I expected to happen was...:
That the dates and times are shown in the format set in the locale settings of the OS, as selected by the user. See the screenshots. In my case as (e.g.)
30 dec 2014 22:04.

What actually happened was...:
Dates and times are shown in the mind-bending headache-inducing USA format. E.g.
12/30/14 10:09 PM

Steps to Reproduce:
1. Start Minecraft
2. Click "Play" in the launcher
3. Click "Singleplayer" in the splash screen
4. If you have existing worlds in Singleplayer, the "Select World" screen now lists these worlds, featuring the wrong date/time format.
5. If you do not yet have a world in Singleplayer, quickly create one, quit it and go to step 3.

Versions of Minecraft affected:
Note: I'd be happy to update the "Affected versions" field of the issue, but the system won't let me
Latest version tried: Minecraft 1.8.1
It looks like this issue has been in Minecraft since the very beginning, and has not been looked at since.

Environment:
For me currently on Mac OS 10.10.1 (Yosemite), but also seen on 10.9.5 (Mavericks)
Also: with Java 6, 7 and 8
Note that the original poster reported this for Windows 7, and there is a confirmation for Linux.

It is probably safe to assume that this issue is independent of the OS and Java environment, and the routine called to print the date/time string does not take localisation settings into account.

Suggestion for solution to this issue:

Currently Minecraft probably uses a simple call with a fixed format (possibly using SimpleDateFormat) to print the date/time strings in the World Selection screen.

Java (naturally) contains calls to print date/time strings in the format as defined by the current Locale. See Class Dateformat.

In particular:

from Class DateFormat

To format a date for the current Locale, use one of the static factory methods:

myString = DateFormat.getDateInstance().format(myDate);

If you are formatting multiple dates, it is more efficient to get the format and use it multiple times so that the system doesn't have to fetch the information about the local language and country conventions multiple times.

DateFormat df = DateFormat.getDateInstance();
  for (int i = 0; i < myDate.length; ++i) {
    output.println(df.format(myDate[i]) + "; ");
  }

I believe putting code similar to the above (probably using getDateTimeInstance() rather than getDateInstance()) in the part of Minecraft where the World Selection screen is generated will solve the issue.

For completeness, search the code for "DateFormat" to see if date/time strings are printed anywhere else in Minecraft, and adjust if appropriate.

Is this still an issue in the most recent versions (currently that is 1.10.2, or 16w43a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.

Yes, this is still an issue with 1.10.2.

Still an issue with 1.11.2. Date printing in US format on non-US locales.

Confirmed for 17w14a

Is this still an issue in the most recent versions (currently that is 1.12.2, or 18w02a) of Minecraft? If so, please update the affected versions and help us keeping this ticket updated from time to time. If you are the owner/reporter of this ticket, you can modify the affected version(s) yourself.

Still unchanged in Minecraft 1.12.2
Can't find any option in the Jira interface to add this to the list of Affected Versions.

@unknown, the ticket is yours now. You can update the list of affected versions yourself now. Maybe you can check it with the latest development snapshot if you're familiar with these.

Can confirm for 1.13 and 18w33a. I use ISO 8601 format and 24 hour time on my Windows 10 PC, but Minecraft displays the dates and times as dd/mm/yy and 12 hour time.

Affects 18w46a

Affects 18w47a

Affects 18w47b

Affects 18w48a

Affects 18w48b, can I request ownership of the ticket?

Affects 18w49a

Changed the reporter to @unknown.

My dates display as dd/mm/yy instead of ISO 8601

The title of this bug should be changed to match that of MC-115414, because as of 21w19a the game actually does recognise the ISO 8601 date format! However, the time settings on my computer are 24 hour time, and the game still displays the time in 12 hour format.

I'm playing on v1.19.31 on PC with my computer set to DD/MM/YY format yet the world selector menu confusingly displays the date in MM/DD/YY format.

How has this still not been fixed years later when the vast, vast majority of the world doesn't use MM/DD/YY, including the developers of the game themselves?

1.19.31 is Bedrock Edition, this bug tracker is for the Java Edition of the game only.

To be a bit more clear, this project (MC) is for Java Edition only, Bedrock edition is MCPE.