Can Instant.toEpochMilli() be used as a unique id?

Question

I have to generate a unique Id which is readable as well hence cannot use UUID. So I thought of using Instant.toEpochMilli(). Can it be used as unique id?

Answer 1

No. I personally faced with situation, when two objects had same id. I have tested System.nanoTime() and it looked OK, but in general case both variants are not correct.

Correct solutions:

• UUID.randomUUID()
• AtomicLong
• Database sequence