Home » Core Java » Java UUID Generator Example

About Yatin

Yatin
The author is graduated in Electronics & Telecommunication. During his studies, he has been involved with a significant number of projects ranging from programming and software engineering to telecommunications analysis. He works as a technical lead in the information technology sector where he is primarily involved with projects based on Java/J2EE technologies platform and novel UI technologies.

Java UUID Generator Example

Hello readers, in this tutorial, we are generating the UUID using the Java and Java UUID Generator API.

1. Introduction

UUID / GUID (Universally / Globally Unique Identifier) is frequently used in programming. Some of its usages are for creating random file names, session id in the web application, transaction id and for record’s primary keys in the database (i.e. replacing the sequence or auto-generated number).

UUID (i.e. Universally Unique Identifier) class is a part of the java.util package and represents an immutable universally unique identifier with a 128 bit number string value. It is represented in 32 Hexadecimal characters and is mixed with 4 dashes (i.e. -) characters. UUID also was known as GUID which stands for Globally Unique Identifier.

Fig. 1: UUID Syntax

Fig. 1: UUID Syntax

Following are the important methods available on the UUID class.

  • String toString(): This method will return a string object representing the UUID
  • int variant(): This method will return the variant number associated with the UUID
  • int version(): This method will return the version number associated with the UUID

Now, open up the Eclipse Ide and let’s see a few examples of how to generate the UUID object in Java!

2. Java UUID Generator Example

2.1 Tools Used

We are using Eclipse Kepler SR2, JDK 8 and Maven. Having said that, we have tested the code against JDK 1.7 and it works well.

2.2 Project Structure

Firstly, let’s review the final project structure, in case you are confused about where you should create the corresponding files or folder later!

Fig.2 : UUID Application Project Structure

Fig.2 : Application Project Structure

2.3 Project Creation

This section will demonstrate on how to create a Java-based Maven project with Eclipse. In Eclipse IDE, go to File -> New -> Maven Project.

Fig. 3: Create Maven Project

Fig. 3: Create Maven Project

In the New Maven Project window, it will ask you to select project location. By default, ‘Use default workspace location’ will be selected. Select the ‘Create a simple project (skip archetype selection)’ checkbox and just click on next button to proceed.

Fig. 4: Project Details

Fig. 4: Project Details

It will ask you to ‘Enter the group and the artifact id for the project’. We will input the details as shown in the below image. The version number will be by default: 0.0.1-SNAPSHOT.

Fig. 5: Archetype Parameters

Fig. 5: Archetype Parameters

Click on Finish and the creation of a maven project is completed. If you observe, it has downloaded the maven dependencies and a pom.xml file will be created. It will have the following code:

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>JavaUuidEx</groupId>
	<artifactId>JavaUuidEx</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>
</project>

Developers can start adding the dependencies that they want to such as UUID Generator etc. Let’s start building the application!

3. Application Building

Below are the steps involved in developing this application.

3.1 Maven Dependencies

Here, we specify the dependencies for the UUID Generator. The rest dependencies will be automatically resolved by the Maven framework and the updated file will have the following code:

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>JavaUuidEx</groupId>
	<artifactId>JavaUuidEx</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<dependencies>
		<dependency>
			<groupId>com.fasterxml.uuid</groupId>
			<artifactId>java-uuid-generator</artifactId>
			<version>3.1.4</version>
		</dependency>
	</dependencies>
	<build>
		<finalName>${project.artifactId}</finalName>
	</build>
</project>

3.2 Java Class Creation

Let’s create the required Java files. Right-click on the src/main/java folder, New -> Package.

Fig. 6: Java Package Creation

Fig. 6: Java Package Creation

A new pop window will open where we will enter the package name as: com.jcg.java.

Fig. 7: Java Package Name (com.jcg.java)

Fig. 7: Java Package Name (com.jcg.java)

Once the package is created in the application, we will need to create the 2 different implementation classes in order to generate the UUID object. Right-click on the newly created package: New -> Class.

Fig. 8: Java Class Creation

Fig. 8: Java Class Creation

A new pop window will open and enter the file name as: UuidExample. The utility class will be created inside the package: com.jcg.java.

Fig. 9: Java Class (UuidExample.java)

Fig. 9: Java Class (UuidExample.java)

Repeat the step (i.e. Fig. 7) and enter the filename as: JugUUIDExample. The main class will be created inside the package: com.jcg.java.

Fig. 10: Java Class (JugUUIDExample.java)

Fig. 10: Java Class (JugUUIDExample.java)

3.2.1 Implementation of Java UUID Class

To generate the UUID object in Java, developers can use the java.util.UUID class which was introduced in JDK 1.5. Let’s see the simple code snippet that follows this implementation.

UuidExample.java

package com.jcg.java;

import java.util.UUID;

public class UuidExample {

	public static void generateRandomUuid(int num) {

		/***** Generate Version 4 UUID - Randomly Generated UUID *****/
		UUID uid = null;
		for(int i=1; i<num; i++) {

			/***** Generating Random UUID's *****/
			uid= UUID.randomUUID();
			System.out.println("Generated UUID?= " + uid.toString() + ", UUID Version?= " + uid.version() + ", UUID Variant?= " + uid.variant() + "\n");
		}
	}

	public static void main(String[] args) {
		int num = 4;
		generateRandomUuid(num);
	}
}

3.2.2 Implementation of Java UUID Generator Class

Developers can use the Java UUID Generator (JUG) utility to generate the UUID object. Let’s see the simple code snippet that follows this implementation.

JugUUIDExample.java

package com.jcg.java;

import java.util.UUID;

import com.fasterxml.uuid.Generators;

public class JugUUIDExample {

	public static void generateRandomUuid() {

		/***** Generate Version 1 UUID - Time-Based UUID *****/
		UUID uuid1 = Generators.timeBasedGenerator().generate();
		System.out.println("Generated Version 1 UUID?= " + uuid1.toString() + ", UUID Version?= " + uuid1.version() + ", UUID Variant?= " + uuid1.version() + "\n");

		/***** Generate Version 4 UUID - Randomly Generated UUID *****/
		UUID uuid2 = Generators.randomBasedGenerator().generate();
		System.out.println("Generated Version 4 UUID?= " + uuid2.toString() + ", UUID Version?= " + uuid2.version() + ", UUID Variant?= " + uuid2.version());
	}

	public static void main(String[] args) {
		generateRandomUuid();
	}
}

Do note, developers will have to use the java-uuid-generator maven dependency for generating the UUID object using the Java UUID Generator class.

4. Run the Application

To run the application, Right-click on the UuidExample class -> Run As -> Java Application. Developers can debug the example and see what happens after every step!

Fig. 11: Run Application

Fig. 11: Run Application

5. Project Demo

The application shows the following logs as output for the UuidExample.java. This class will randomly generate a Version 4 UUID object.

Generated UUID?= 771cdd2e-e524-4218-b0da-21d0fd9a5307, UUID Version?= 4, UUID Variant?= 2

Generated UUID?= 16caf416-2434-42f5-ac5c-031bc3787247, UUID Version?= 4, UUID Variant?= 2

Generated UUID?= a42ac726-f54a-4094-a4d2-b7d1c70f9237, UUID Version?= 4, UUID Variant?= 2

The JugUUIDExample.java will generate a Version 1 and Version 4 UUID object and shows the following logs as output.

Generated Version 1 UUID?= c1336282-f08b-11e7-b344-c74db8d97c98, UUID Version?= 1, UUID Variant?= 1

Generated Version 4 UUID?= f803c0bc-ae39-4d1b-83c0-bcae392d1bd5, UUID Version?= 4, UUID Variant?= 4

That’s all for this post. Happy Learning!!

6. Conclusion

That’s all for Java UUID class and developers can use it to create the unique identifiers for their application. I hope this article served you whatever you were looking for.

7. Download the Eclipse Project

This was an example of Java UUID Generator for the beginners.

Download
You can download the full source code of this example here: JavaUuidEx
(No Ratings Yet)
Start the discussion Views Tweet it!

Do you want to know how to develop your skillset to become a Java Rockstar?

Subscribe to our newsletter to start Rocking right now!

To get you started we give you our best selling eBooks for FREE!

 

1. JPA Mini Book

2. JVM Troubleshooting Guide

3. JUnit Tutorial for Unit Testing

4. Java Annotations Tutorial

5. Java Interview Questions

6. Spring Interview Questions

7. Android UI Design

 

and many more ....

 

Receive Java & Developer job alerts in your Area

 

Leave a Reply

avatar
  Subscribe  
Notify of