datafaker

Generating fake data for the JVM (Java, Kotlin, Groovy) has never been easier!

1,137

156

1,137

View on GitHub

Top Related Projects

Bogus

8,653

:card_index: A simple fake data generator for C#, F#, and VB.NET. Based on and ported from the famed faker.js.

java-faker

4,697

Brings the popular ruby faker gem to Java

faker

11,223

A library for generating fake data such as names, addresses, and phone numbers.

Quick Overview

Datafaker is a Java library that generates fake data for testing and development purposes. It provides a wide range of data types and customizable options, allowing developers to create realistic and diverse datasets quickly and easily.

Pros

Extensive variety of data types and generators
Highly customizable and flexible
Easy to integrate with existing Java projects
Active development and community support

Cons

Limited documentation for advanced use cases
Some generators may produce repetitive data in large datasets
Performance can be slower for very large data generation tasks
Primarily focused on Java, with limited support for other languages

Code Examples

Generate a random name:

Faker faker = new Faker();
String name = faker.name().fullName();
System.out.println(name);

Generate a list of 5 random email addresses:

Faker faker = new Faker();
List<String> emails = faker.collection(
    () -> faker.internet().emailAddress()
).len(5).generate();
emails.forEach(System.out::println);

Generate a custom object with fake data:

Faker faker = new Faker();
Person person = faker.expression("#{create('com.example.Person', 'name', '#{name.fullName}', 'age', '#{number.numberBetween '18','80'}')}");
System.out.println(person);

Getting Started

To use Datafaker in your Java project, add the following dependency to your Maven pom.xml file:

<dependency>
    <groupId>net.datafaker</groupId>
    <artifactId>datafaker</artifactId>
    <version>1.8.1</version>
</dependency>

For Gradle, add this to your build.gradle file:

implementation 'net.datafaker:datafaker:1.8.1'

Then, you can start using Datafaker in your Java code:

import net.datafaker.Faker;

public class Example {
    public static void main(String[] args) {
        Faker faker = new Faker();
        System.out.println(faker.name().fullName());
        System.out.println(faker.address().cityName());
        System.out.println(faker.date().birthday());
    }
}

This will generate and print a random full name, city name, and birthday.

Competitor Comparisons

Bogus

8,653

:card_index: A simple fake data generator for C#, F#, and VB.NET. Based on and ported from the famed faker.js.

Pros of Bogus

More mature project with a longer history and larger community
Extensive documentation and examples available
Supports localization for multiple languages out of the box

Cons of Bogus

Limited to .NET ecosystem, while Datafaker supports multiple languages
Less frequent updates and releases compared to Datafaker
Smaller set of built-in data providers

Code Comparison

Bogus:

var faker = new Faker("en");
var user = new Faker<User>()
    .RuleFor(u => u.FirstName, f => f.Name.FirstName())
    .RuleFor(u => u.LastName, f => f.Name.LastName())
    .Generate();

Datafaker:

Faker faker = new Faker();
User user = new User(
    faker.name().firstName(),
    faker.name().lastName()
);

Both libraries offer similar functionality for generating fake data, with slight differences in syntax and method names. Bogus uses a fluent interface with rules, while Datafaker uses direct method calls on the faker instance.

java-faker

4,697

Brings the popular ruby faker gem to Java

Pros of java-faker

More established project with longer history and larger community
Extensive documentation and examples available
Supports a wide range of locales for internationalization

Cons of java-faker

Less frequent updates and slower development cycle
Limited support for custom data providers
Lacks some advanced features found in newer libraries

Code Comparison

java-faker:

Faker faker = new Faker();
String name = faker.name().fullName();
String streetAddress = faker.address().streetAddress();

datafaker:

Faker faker = new Faker();
String name = faker.name().fullName();
String streetAddress = faker.address().streetAddress();

The basic usage of both libraries is very similar, with nearly identical method calls for generating fake data. However, datafaker offers additional features and customization options not shown in this basic example.

datafaker builds upon the foundation laid by java-faker, extending its functionality while maintaining compatibility with existing code. It provides more frequent updates, additional data providers, and advanced features like customizable locales and improved performance.

While java-faker remains a solid choice for basic fake data generation, datafaker offers a more modern and feature-rich alternative, especially for projects requiring extensive customization or advanced data generation capabilities.

faker

11,223

A library for generating fake data such as names, addresses, and phone numbers.

Pros of Faker

Mature and well-established library with a large community
Extensive documentation and examples
Supports multiple locales for internationalization

Cons of Faker

Limited to Ruby programming language
Slower performance compared to Datafaker
Less frequent updates and maintenance

Code Comparison

Faker (Ruby):

require 'faker'

Faker::Name.name
Faker::Internet.email
Faker::Address.street_address

Datafaker (.NET):

using Bogus;

var faker = new Faker();
faker.Name.FullName();
faker.Internet.Email();
faker.Address.StreetAddress();

Key Differences

Language: Faker is for Ruby, while Datafaker is for .NET
Performance: Datafaker generally offers better performance
API: Similar API structure, but with language-specific implementations
Community: Faker has a larger community due to its longer existence
Features: Both offer similar core features, but Datafaker includes some additional functionalities

Use Cases

Faker: Ideal for Ruby projects requiring fake data generation
Datafaker: Best suited for .NET applications needing efficient data faking

Both libraries serve similar purposes but cater to different programming ecosystems. The choice between them largely depends on the development platform and specific project requirements.

Convert designs to code with AI

Introducing Visual Copilot: A new AI model to turn Figma designs to high quality code using your components.

Try Visual Copilot

README

Datafaker

This library is a modern fork of java-faker with up to date libraries and several newly added Fake Generators.

Datafaker 2.x has Java 17 as the minimum requirement.

If Java 17 is not an option for you, you can choose to use Datafaker 1.x. Datafaker 1.x is built on Java 8, but this version is no longer maintained. We recommend all users to upgrade to Datafaker 2.x.

This library generates fake data, similar to other fake data generators, such as:

Ruby's faker gem
Perl's Data::Faker library
Python faker package
PHP faker library
Javascript Faker.js library

It's useful when you're developing a new project and need some pretty data for showcase.

Usage

In the pom.xml, add the following fragment to the dependencies section:

<dependency>
    <groupId>net.datafaker</groupId>
    <artifactId>datafaker</artifactId>
    <version>2.3.1</version>
</dependency>

For Gradle users, add the following to your build.gradle file.

dependencies {
    implementation 'net.datafaker:datafaker:2.3.1'
}

You can also use the snapshot version (2.3.2-SNAPSHOT), which automatically gets published after every push to the main branch of this repository. Binary repository URL for snapshots download is https://s01.oss.sonatype.org/content/repositories/snapshots/.

Get started

In your Java code:

Faker faker = new Faker();

String name = faker.name().fullName(); // Miss Samanta Schmidt
String firstName = faker.name().firstName(); // Emory
String lastName = faker.name().lastName(); // Barton

String streetAddress = faker.address().streetAddress(); // 60018 Sawayn Brooks Suite 449

Or in your Kotlin code:

val faker = Faker()

val name = faker.name().fullName() // Miss Samanta Schmidt
val firstName = faker.name().firstName() // Emory
val lastName = faker.name().lastName() // Barton

val streetAddress = faker.address().streetAddress() // 60018 Sawayn Brooks Suite 449

JShell

# from project root folder
jshell --class-path $(ls -d target/*.jar | tr '\n' ':')
|  Welcome to JShell -- Version 17.0.4
|  For an introduction type: /help intro

jshell> import net.datafaker.Faker;

jshell> var faker = new Faker();
faker ==> net.datafaker.Faker@c4437c4

jshell> faker.address().city();
$3 ==> "Brittneymouth"

jshell> faker.name().fullName();
$5 ==> "Vernie Schmidt"

Expressions

Faker faker = new Faker();
faker.expression("#{letterify 'test????test'}"); // testqwastest
faker.expression("#{numerify '#test#'}"); // 3test5
faker.expression("#{templatify 'test','t','q','@'}"); // @esq
faker.expression("#{examplify 'test'}"); // ghjk
faker.expression("#{regexify '[a-z]{4,10}'}"); // wbevoa
faker.expression("#{options.option '23','2','5','$','%','*'}"); // *
faker.expression("#{date.birthday 'yy DDD hh:mm:ss'}"); // 61 327 08:11:45
faker.expression("#{csv '1','name_column','#{Name.first_name}','last_name_column','#{Name.last_name}'}");
// "name_column","last_name_column"
// "Sabrina","Kihn"
faker.expression("#{json 'person','#{json ''first_name'',''#{Name.first_name}'',''last_name'',''#{Name.last_name}''}','address','#{json ''country'',''#{Address.country}'',''city'',''#{Address.city}''}'}");
// {"person": {"first_name": "Barbie", "last_name": "Durgan"}, "address": {"country": "Albania", "city": "East Catarinahaven"}}

also more examples at https://www.datafaker.net/documentation/expressions/

Collections

Faker faker = new Faker();
List<String> names = faker.collection(
                              () -> faker.name().firstName(),
                              () -> faker.name().lastName())
                         .len(3, 5)
                         .generate();
System.out.println(names);
// [Skiles, O'Connell, Lorenzo, West]

more examples about that at https://www.datafaker.net/documentation/sequences/

Streams

Faker faker = new Faker();
// generate an infinite stream
Stream<String> names = faker.stream(
                              () -> faker.name().firstName(),
                              () -> faker.name().lastName())
                         .generate();

Formats

Schema

There are 2 ways of data generation in specific formats

Generate it from scratch
There is already a sequence of objects and we could extract from them some values and return it in specific format

For both cases we need a Schema which could describe fields and a way of data generation. In case of generation from scratch Suppliers are enough, in case of transformation Functions are required

CSV

// transformer could be the same for both
CsvTransformer<Name> transformer =
        CsvTransformer.<Name>builder().header(true).separator(",").build();
// Schema for from scratch
Schema<Name, String> fromScratch =
    Schema.of(field("firstName", () -> faker.name().firstName()),
        field("lastname", () -> faker.name().lastName()));
System.out.println(transformer.generate(fromScratch, 2));
// POSSIBLE OUTPUT
// "first_name" ; "last_name"
// "Kimberely" ; "Considine"
// "Mariela" ; "Krajcik"
// ----------------------
// Schema for transformations
Schema<Name, String> schemaForTransformations =
    Schema.of(field("firstName", Name::firstName),
        field("lastname", Name::lastName));
// Here we pass a collection of Name objects and extract first and lastnames from each element
System.out.println(
    transformer.generate(
        faker.collection(faker::name).maxLen(2).generate(), schemaForTransformations));
// POSSIBLE OUTPUT
// "first_name" ; "last_name"
// "Kimberely" ; "Considine"
// "Mariela" ; "Krajcik"

JShell

# from project root folder
jshell --class-path $(ls -d target/*.jar | tr '\n' ':')
|  Welcome to JShell -- Version 17.0.4
|  For an introduction type: /help intro

jshell> import net.datafaker.Faker;

jshell> import net.datafaker.providers.base.Name;

jshell> import net.datafaker.transformations.Schema;

jshell> import net.datafaker.transformations.CsvTransformer;

jshell> import static net.datafaker.transformations.Field.field;

jshell> var faker = new Faker();
faker ==> net.datafaker.Faker@c4437c4

jshell> Schema fromScratch =
   ...>     Schema.of(field("firstName", () -> faker.name().firstName()),
   ...>         field("lastname", () -> faker.name().lastName()));
fromScratch ==> net.datafaker.transformations.Schema@306a30c7

jshell> CsvTransformer<Name> transformer =
   ...>     CsvTransformer.<Name>builder().header(false).separator(",").build();
transformer ==> net.datafaker.transformations.CsvTransformer@506c589e

jshell> System.out.println(transformer.generate(fromScratch, 2));
"firstName","lastname"
"Darcel","Schuppe"
"Noelle","Smitham"

JSON

Schema<Object, ?> schema = Schema.of(
    field("firstName", () -> faker.name().firstName()),
    field("lastName", () -> faker.name().lastName())
    );

JsonTransformer<Object> transformer = JsonTransformer.builder().build();
String json = transformer.generate(schema, 2);
// [{"firstName": "Oleta", "lastName": "Toy"},
// {"firstName": "Gerard", "lastName": "Windler"}]

More complex examples and other formats like YAML, XML could be found at https://www.datafaker.net/documentation/formats/

Unique Values

Faker faker = new Faker();

// The values returned in the following lines will never be the same.
String firstUniqueInstrument = faker.unique().fetchFromYaml("music.instruments"); // "Flute"
String secondUniqueInstrument = faker.unique().fetchFromYaml("music.instruments"); // "Clarinet"

More examples can be found in https://www.datafaker.net/documentation/unique-values

Custom provider

Add your own custom provider in your app following steps from https://www.datafaker.net/documentation/custom-providers/

Documentation

Getting started.

Contributions

See CONTRIBUTING.md

If this is your first time contributing then you may find it helpful to read FIRST_TIME_CONTRIBUTOR.md

Providers

The list below is not complete and shows only a part of available providers. To view the full list of providers, please follow the link: Full list of providers.

Address
Ancient
Animal
App
Appliance
Aqua Teen Hunger Force
Artist
Australia
Avatar
Aviation
AWS
Azure
Babylon 5
Back To The Future
Barcode
Baseball
Basketball
Battlefield 1
Beer
Big Bang Theory
Blood Type
Boardgame
Bojack Horseman
Book
Bool
Bossa Nova
Brand
Breaking Bad
Brooklyn Nine-Nine
Buffy
Business
CNPJ (Brazilian National Registry of Legal Entities)
CPF (Brazilian individual taxpayer registry identification)
Camera
Cat
Chuck Norris
Clash of Clans
Code
Coin
Color
Commerce
Community
Company
Compass
Computer
Control
Country
Credit Card Type
Cricket
Crypto
Currency
Date and Time
DC Comics
Demographic
Departed
Dessert
Device
Disease
Doctor Who
Dog
Domain
Doraemon
Dota 2
Dragon Ball
Driving License
Dumb and Dumber
Dune
Durations
Educator
Elden Ring
Elder Scrolls
Electrical Components
Emoji
England Football
Esports
Fallout
Family Guy
Famous Last Words
File
Final Space
Finance
Food
Formula 1 (:racing_car:)
Friends
Fullmetal Alchemist: Brotherhood
Funny Name
Futurama
Game Of Thrones
Garment Size
Gender
Ghostbusters
Grateful Dead
Greek Philosopher
Hacker
Harry Potter
Hashing
Hearthstone
Heroes of the Storm
Hey Arnold
Hipster
Hitchhiker's Guide To The Galaxy
Hobbit
Hobby
Horse
House
How I Met Your Mother
IdNumber
Industry Segments
Internet
Job
Joke
K-pop (Korean popular music)
Kaamelott
Language Code
League Of Legends
Lebowski
Locality
Lord Of The Rings
Lorem
Marketing
Marvel Snap
Mass Effect
Matz
MBTI
Measurement
Medical
Military
Minecraft
Money
Money Heist
Mood
Mountaineering
Mountains
Movie
Music
Name
Naruto
Nation
Nato Phonetic Alphabet
Nigeria
Number
One Piece
Options
Oscar Movie
Overwatch
Passport
Password
Phone Number
Photography
Planet
Pokemon
Princess Bride
Programming Language
Red Dead Redemption 2
Relationship Terms
Resident Evil
Restaurant
Rick and Morty
Robin
Rock Band
RuPaul's Drag Race
Science
Seinfeld
Shakespeare
Silicon Valley
Simpsons
Sip
Size
Slack Emoji
Soul Knight
Space
StarCraft
StarTrek
Stock
Studio Ghibli
Subscription
Super Mario
Superhero
Tea
Team
The IT Crowd
Time
Touhou
Tron
Twin Peaks
Twitter
University
Vehicle
Verb
Volleyball
Weather
Witcher
Yoda
Zelda

Usage with Locales

Faker faker = new Faker(new Locale("lang", "COUNTRY"));

For example:

String californiaZipCode = new Faker(new Locale("en", "US")).address().zipCodeByState("CA");
String albanianIdNumber = new Faker(new Locale("sq", "AL")).idNumber().valid();
String moldovanPhone = new Faker(new Locale("ru", "MD")).phoneNumber().cellPhone();

Note that most of the data depends on language, but some data depends purely on country (personal ID and phone numbers). In the example above,

"en", "sq", "ru" are language codes (English, Albanian and Russian), and
"US", "AL", "MD" are country codes (USA, Albanian and Moldova)

Supported Locales

ar (Armenian)
be_BY (Belarusian)
bg_BG (Bulgarian)
ca_CA
ca-CAT
cs_CZ (Czech republic)
da-DK
de
de-AT
de_CH (country: Switzerland, language: German)
el-GR
en
en-AU
en-au-ocker
en-BORK
en-CA
en-GB
en-IND
en-MS
en-NEP
en-NG
en-NZ
en-PAK
en-SG
en-UG
en-US
en-ZA
en-PH
es_ES (Spain)
es-MX (Mexican)
et_EE (Estonian)
fa
fi-FI
fr_FR (French)
fr_CH (country: Switzerland, language: French)
ge_GE (Georgia)
he_IL (language: Hebrew, country: Israel)
hr_HR (Croatian)
hu_HU (Hungarian)
hy_AM (Armenian)
in-ID (Indonesia)
it
ja
ka
ko
mk_MK (North Macedonia)
nb-NO
nl
pl
pt
pt-BR
ro_MD (country: Moldova, language: Moldavian a.k.a. Romanian)
ru_RU (Russian)
sk_SK (Slovak)
sq_AL (Albanian)
sv
sv-SE
tr
th_TH (Thailand)
uk
vi
zh_CN (Chinese)
zh-TW

LICENSE

Top Related Projects

Convert designs to code with AI

Introducing Visual Copilot: A new AI model to turn Figma designs to high quality code using your components.

Try Visual Copilot