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17 is not an option for you, you can choose to use Datafaker 1.x. Datafaker 1.x is built on Java 8, but this version is no longer maintained.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>2.5.4</version>
</dependency>

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

dependencies {
    implementation 'net.datafaker:datafaker:2.5.4'
}

You can also use the snapshot version (2.6.0-SNAPSHOT), which automatically gets published after every push to the main branch of this repository. Binary repository URL for snapshots download is https://central.sonatype.com/repository/maven-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' ':')

or JShell w/JBang

# can be run anywhere, no project root/download needed.
jbang -i net.datafaker:datafaker:2.5.4

|  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
Apple
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
D

Datafaker

Install / Use

README

Datafaker

Usage

Get started

Expressions

Collections

Streams

Formats

Schema

CSV

JShell

JSON

Unique Values

Custom provider

Documentation

Contributions

Providers