Answer by user_3380739 for How to generate a random alpha-numeric string?

Here is the one line code by AbacusUtil

String.valueOf(CharStream.random('0', 'z').filter(c -> N.isLetterOrDigit(c)).limit(12).toArray())

Random doesn't mean it must be unique. to get unique strings, using:

N.uuid() // e.g.: "e812e749-cf4c-4959-8ee1-57829a69a80f". length is 36.
N.guid() // e.g.: "0678ce04e18945559ba82ddeccaabfcd". length is 32 without '-'