How do I extract a date from a UUID using Java? [closed]

Question

How to convert the UUID to date format 2011-04-22 ?

For example, I have UUID like this

118ffe80-466b-11e1-b5a5-5732cf729524.

How to convert this to date format?

I tried

 String uuid="118ffe80-466b-11e1-b5a5-5732cf729524"; 
    UUID uid = UUID.fromString(uuid);
    long ls=convertTime(uid.timeStamp()); // it returns long value

    public String convertTime(long time){
            System.out.println("====="+time);
            Date date = new Date(time);
            Format format = new SimpleDateFormat("yyyy/MM/dd");
            return format.format(date).toString();
        }

output I got:4294744/11/02

Same case working fine for perl

$uuid='ef802820-46b3-11e2-bf3a-47ef6b3e28e2';
$uuid =~ s/-//g;

my $timelow = hex substr( $uuid, 2 * 0,     2 * 4 );
my $timemid = hex substr( $uuid, 2 * 4,     2 * 2 );
my $version = hex substr( $uuid, 2 * 6,     1 );
my $timehi  = hex substr( $uuid, 2 * 6 + 1, 2 * 2 - 1 );

my $time = ( $timehi * ( 2**16 ) + $timemid ) * ( 2**32 ) + $timelow;
my $epoc = int( $time / 10000000 ) - 12219292800;
my $nano = $time - int( $time / 10000000 ) * 10000000;

#$time_date = scalar localtime $epoc;
#print strftime( '%d-%m-%Y %H:%M:%S', localtime($epoc) );
#print "\n Time: ", scalar localtime $epoc, " +", $nano / 10000, "ms\n";

Answer 1

The javadoc for UUID says the following about the timestamp field:

The 60 bit timestamp value is constructed from the time_low, time_mid, and time_hi fields of this UUID. The resulting timestamp is measured in 100-nanosecond units since midnight, October 15, 1582 UTC.

(emphasis mine)

The Java timestamp is in milliseconds since 1970-01-01. In order to get a meaningful date from a UUID, you'll need to do two things: convert from 100ns to 1ms precision (divide by 10000) and rebase from 1582-10-15 to 1970-01-01, which you can do by adding a constant value.

WolframAlpha tells us that 1582-10-15 corresponds to a UNIX timestamp of -12219292800, so to get the correct date, you must add 12219292800 to the number of milliseconds you got after dividing by 10000.

As a side note:

The timestamp value is only meaningful in a time-based UUID, which has version type 1. If this UUID is not a time-based UUID then this method throws UnsupportedOperationException.

...so make sure your code either only ever encounters Type 1 UUID's, or can handle that they don't have a timestamp.