How to Generate UUID in Java

How to Generate a UUID in Java

The standard way to generate a UUID in Java is UUID.randomUUID(), built into the JDK since Java 1.5 — no dependencies, no configuration required. It draws from a cryptographically secure random source to produce a 128-bit identifier with virtually no chance of collision. The python uuid generator guide includes production patterns for FastAPI, SQLAlchemy, and bulk generation scripts.

Main.java

import java.util.UUID;

public class Main {
    public static void main(String[] args) {
        UUID uuid = UUID.randomUUID();
        System.out.println(uuid);
        // Output: 550e8400-e29b-41d4-a716-446655440000
    }
}

Explanation

import java.util.UUID; loads the JDK's built-in UUID class — no Maven or Gradle dependency needed.
UUID.randomUUID() generates a random UUID (version 4) using a cryptographically strong SecureRandom instance internally.
System.out.println(uuid) calls the UUID object's toString() method automatically, producing the standard 36-character hyphenated format.
The result is a UUID object, not a String — call .toString() explicitly when you need a string for concatenation, JSON serialization, or database storage.

Convert a String to a UUID in Java

Sometimes a UUID arrives as a plain string — from a REST request, a config file, or a database column — and you need it back as a proper UUID object. UUID.fromString() handles this in one line. The mysql uuid page includes examples for MySQL 8.0+ with UUID_TO_BIN() for storage-efficient identifiers.

Main.java

import java.util.UUID;

public class Main {
    public static void main(String[] args) {
        UUID original = UUID.randomUUID();
        String uuidString = original.toString();

        // Parse the string back into a UUID object
        UUID parsed = UUID.fromString(uuidString);
        System.out.println(original.equals(parsed));
        // Output: true
    }
}

Explanation

UUID.fromString() is a static factory method that parses any valid 36-character hyphenated UUID string into a UUID object.
It throws IllegalArgumentException if the string is malformed, so wrap the call in a try/catch block when parsing untrusted input.
.equals() compares two UUID objects by value, returning true when they represent the same identifier regardless of how each was created.
Use this round-trip pattern to validate incoming UUIDs from API requests or database rows before trusting them.

Other Options for Generating UUIDs in Java

java.util.UUID covers random (v4) and name-based (v3) generation, but it has no native support for UUID v7, the newer time-sortable format increasingly used for database primary keys. The third-party uuid-creator library fills that gap.

pom.xml

<dependency>
    <groupId>com.github.f4b6a3</groupId>
    <artifactId>uuid-creator</artifactId>
    <version>5.3.7</version>
</dependency>

Main.java

import com.github.f4b6a3.uuid.UuidCreator;
import java.util.UUID;

public class Main {
    public static void main(String[] args) {
        // UUID v7 - Unix timestamp + random, sortable and index-friendly
        UUID uuidV7 = UuidCreator.getTimeOrderedEpoch();
        System.out.println(uuidV7);
    }
}

Explanation

Adding com.github.f4b6a3:uuid-creator to your pom.xml or build.gradle pulls in RFC 9562-compliant v7 generation that the JDK doesn't provide.
UuidCreator.getTimeOrderedEpoch() encodes the current Unix millisecond timestamp in the most significant bits, so generated IDs sort chronologically — ideal for database primary keys and index locality.
The returned value is still a standard java.util.UUID, so it works everywhere a JDK UUID does — JPA entities, JSON serialization, Comparable sorting.
java.util.UUID remains the right choice for v4 (random) and v3 (name-based) generation; reach for uuid-creator only when you specifically need v7 (or v1/v6) chronological ordering.

Generate UUID in Java

How to Generate a UUID in Java

Explanation

Convert a String to a UUID in Java

Explanation

Other Options for Generating UUIDs in Java

Explanation

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