Generate random numbers using Javafaker API – Java
Introduction
We may require to generate random numbers in programming languages for multiple purposes like test data creation or numeric IDs for employees etc. We have multiple libraries available to generate random numbers in Java but I personally feel Javafaker APIs are easier to use compared to others.
We will learn to generate random whole numbers, decimal numbers, and also within a range in this post.
I have covered an introductory post on Javafaker API here.
Maven Dependency
I have used below Javafaker API dependency:-
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<!-- https://mvnrepository.com/artifact/com.github.javafaker/javafaker --> <dependency> <groupId>com.github.javafaker</groupId> <artifactId>javafaker</artifactId> <version>1.0.2</version> </dependency> |
Generate random numbers
Faker class in Javafaker library provides utility methods for generating fake strings, such as names, phone numbers, addresses. generate random strings with given patterns.
Generate a random digit
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package FakerClassExamples; import com.github.javafaker.Faker; public class RandomNumberExample { public static void main(String[] args) { Faker faker = new Faker(); // Generate random digit between 0 - 9 both inclusive System.out.println(faker.number().digit()); System.out.println(faker.number().randomDigit()); // Generate random digit between 1 - 9 both inclusive System.out.println(faker.number().randomDigitNotZero()); // Generate digit of specific length System.out.println(faker.number().digits(3)); System.out.println(faker.number().digits(5)); } } |
Output
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5 3 6 608 72863 |
Generate number within a range
Generating a random number within a range is required at many times and I think Javafaker provides the easiest way to do so.
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package FakerClassExamples; import com.github.javafaker.Faker; public class RandomNumberWithinRange { public static void main(String[] args) { Faker faker = new Faker(); // Generate a number between 1(inclusive) to 999 (exclusive) System.out.println(faker.number().numberBetween(1, 999)); // Generate a decimal random number within range System.out.println(faker.number().randomDouble(4, 10, 100)); } } |
Output
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726 89.193 |
There are many useful methods provided by the Javafaker library which you can explore and learn about.
You can clone above Git Repo from here.
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Thank you for sharing this important concept. and its very simple to implement and very helpful in generating test data