UUIDs are handy for giving entities their own special names, for example, in a database. There are several ways to generate them, including methods based on time, MAC addresses, hashes, and random numbers, but they make the same promise: no two are identical. Each one is unique across space and time.

Is Java UUID globally unique?

It is also known as a Globally Unique Identifier (GUID). A UUID is a class that represents an immutable Universally Unique Identifier (UUID). A UUID represents a 128-bit long value that is unique to all practical purpose.

Is UUID always the same?

No, a UUID can’t be guaranteed to be unique. A UUID is just a 128-bit random number. When my computer generates a UUID, there’s no practical way it can prevent your computer or any other device in the universe from generating that same UUID at some time in the future.