java.util · java.base · since Java 1.5

UUID

declaration

public final class UUID implements Serializable, Comparable<UUID>

128-bit universally unique identifier. randomUUID() (v4) is the standard for distributed ids; string round-trips via toString/fromString.

Key methods

`static UUID randomUUID()`	Cryptographically random v4 — the everyday factory.
`static UUID fromString(String name)`	Parse the 8-4-4-4-12 form.