Java: Randomly generate distinct names

Question

I need to generate 10,000 unique identifiers in Java. The identifiers should be a mixture of numbers and letters and less than 10 characters each. Any ideas? Built in librar

Answer 1

I had the same problem, but I needed an arbitrarily long string. I came up with this one-liner, no external library needed, that will give you 10 characters:

BigInteger.probablePrime(50, new Random()).toString(Character.MAX_RADIX)

The length can be changed, you need about 5 bits per character. What did is filter and limit the length as follows (just lowercase letters, and size 10):

BigInteger.probablePrime(100, new Random()).
    toString(Character.MAX_RADIX).
    replaceAll("[0-9]", "").
    substring(0, 10) 

Disadvantage: it's a bit slow.