UUID stands for Universally Unique Identifier. It is a unique identifier with 128-bit number string (RFC 4122). It represented in 32 Hexadecimal characters and mixed with 4 dash -
characters.
UUID also known as GUID which stands for Globally Unique Identifier.
In software development, UUID can be generated and used it as:
- Session ID in web application
- Primary key in database’s table
- Transaction ID
- Random filename creation
In this tutorial, we’ll show you few examples of how to generate UUID in Java.
What You’ll Need
- Oracle JDK 1.6 or above
- Java UUID Generator 3.1.4
Example 1: java.util.UUID
Use JDK java.util.UUID
class to generate version 4 UUID which is randomly generated UUID.
Example code:
GenerateUUIDExample.java
import java.util.UUID;
public class GenerateUUIDExample {
public static void main(String[] args) {
// Generate version 4 UUID - Randomly generated UUID
UUID uuid = UUID.randomUUID();
System.out.println("Generated UUID: " + uuid.toString());
System.out.println("UUID version : " + uuid.version());
System.out.println("UUID variant : " + uuid.variant());
}
}
Output:
Generated UUID: 3642d408-92e5-42fa-a32a-b4ff0a878eb9
UUID version : 4
UUID variant : 2
Example 2: Java UUID Generator
Use Java UUID Generator (JUG) to generate UUID. This is the example of version 1 UUID and version 4 UUID generation.
Maven dependency:
<dependency>
<groupId>com.fasterxml.uuid</groupId>
<artifactId>java-uuid-generator</artifactId>
<version>3.1.4</version>
</dependency>
Example code:
JugUUIDExample.java
import java.util.UUID;
import com.fasterxml.uuid.Generators;
public class JugUUIDExample {
public static void main(String[] args) {
// Generate version 1 UUID - Time-based UUID
UUID uuid2 = Generators.timeBasedGenerator().generate();
System.out.println("Generated version 1 UUID: " + uuid2.toString());
System.out.println("Version 1 UUID version : " + uuid2.version());
System.out.println("Version 1 UUID variant : " + uuid2.variant());
// Generate version 4 UUID - Randomly generated UUID
UUID uuid1 = Generators.randomBasedGenerator().generate();
System.out.println("Generated version 4 UUID: " + uuid1.toString());
System.out.println("version 4 UUID version : " + uuid1.version());
System.out.println("version 4 UUID variant : " + uuid1.variant());
}
}
Output:
Generated version 1 UUID: 8d443d10-2ebf-11e7-a09a-1d5a93496478
Version 1 UUID version : 1
Version 1 UUID variant : 2
Generated version 4 UUID: adfabcb7-6fc5-42c8-babc-b76fc532c8dc
version 4 UUID version : 4
version 4 UUID variant : 2
Summary
In this tutorial, we have shown you several examples of generating UUID in Java.