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UUID Identifiers

UUID models a 128-bit identifier and provides parsing, formatting and generation. A UUID identifies a record; it does not grant access to that record. Save as Main.java and run with a Java 17+ JDK: java Main.java.

Syntax

UUID.fromString(text); UUID.randomUUID()

Examples

UUID Identifiers

Save as Main.java and run with a Java 17+ JDK: java Main.java.

import java.util.UUID;

public class Main {
  public static void main(String[] args) throws Exception {
    UUID id = UUID.fromString("550e8400-e29b-41d4-a716-446655440000");
    System.out.println(id.version());
    System.out.println(id.toString());
  }
}
  1. Expected output: 4 550e8400-e29b-41d4-a716-446655440000
  2. The fixed value makes the example repeatable. randomUUID creates a new version-4 UUID when a fresh identifier is needed.

Best practices

  • Store UUID values in a consistent representation.
  • Validate authorization independently of whether an identifier is difficult to guess.

Runtime & versions

Java Virtual Machine. Feature availability depends on the language and runtime version used by your project; consult the official reference below.

Java Language Specification

Specifications & further reading