8 chars unique String in Java

Question

Is there any way to generate 8 characters long random and unique String in Java?

String id = getRandomString();

and then id will be for example wf41Av5g

Answer 1

The uniqueness property depends on the scope in which you use it. Java can certainly generate random strings, although if you want a universally unique identifier you can use UUID class.

String unique = UUID.randomUUID().toString();

Answer 2

If the uniqueness is important, you can't simply randomly generate strings. There is no way to avoid a collision. Even UUIDs can collide, although it is quite unlikely.

You could keep a record of the strings you've used, and when you generate a new random string, check the record to see if it's a duplicate, and if so, discard it and try again.

However, what i would suggest is that you don't generate random numbers. Instead, keep a counter, and encrypt its output to produce random-looking numbers. These are guaranteed never to collide if you do this properly. See an earlier answer of mine, or one by Rossum