Shortening java UUID while preserving the uniqueness

I'm trying to make the java UUID shorter while preserving the same uniqueness as the UUID has. I wrote the following code: ``` public static void main(String[] args) { UUID uid=UUID.randomUUID(); String shortId=to62System(uid.getMostSignificantBits())+ to62System(uid.getLeastSignificantBits()); System.out.println(shortId); } static char[] DIGITS = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray(); static int RADIX = DIGITS.length; public static String to62System(long value) { if (value == 0) { return "0"; } else { char[] buf = new char[11]; int charPos = 10; long i = value; while (i != 0) { buf[charPos--] = DIGITS[Math.abs((int) (i % RADIX))]; i /= RADIX; } return new String(buf, charPos + 1, (10 - charPos)); } } ``` Am I doing it right or did I overlooked something important?