What is RandomStringUtils.randomNumeric() in Java?

Overview

randomNumeric() is a staticdescribes the methods in Java that can be called without creating an object of the class method of the RandomStringUtils class which is used to generate random string consisting of numeric characters.

Characters will be chosen from the set of characters that matches the regex class Digit. The regex \p{Digit} matches all the characters that are digits.

There are two variations to this method.

Variation 1

This variation of the method creates a random string whose length is the number of characters specified.

Syntax

public static String randomNumeric(final int count)

Parameters

final int count: the length of random string to generate.

Return Value

The method returns a random string.

Variation 2

This variation of the method creates a random string whose length is between the inclusive minimum and the exclusive maximum.

Syntax

public static String randomNumeric(final int minLengthInclusive, final int maxLengthExclusive)

Parameters

final int minLengthInclusive: The inclusive minimum length of the string to generate.
final int maxLengthExclusive: The exclusive maximum length of the string to generate.

Return Value

The method returns a random string.

How to import `RandomStringUtils`

The definition of RandomStringUtils can be found in the Apache Commons Lang package, which we can add to the Maven project by adding the following dependency to the pom.xml file:

<dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.12.0</version>
</dependency>

For other versions of the commons-lang package, refer to the Maven Repository.

You can import the RandomStringUtils class as follows:

import org.apache.commons.lang3.RandomStringUtils;

import org.apache.commons.lang3.RandomStringUtils;
public class Main{
    public static void main(String[] args){
        int count = 5;
        System.out.println("The output of RandomStringUtils.randomNumeric when the length is " + count + " - " + RandomStringUtils.randomNumeric(count));
        int minLength = 5;
        int maxLength = 10;
        System.out.println("The output of RandomStringUtils.randomNumeric when the (minlength, maxlength) is (" + minLength + ", " + maxLength + ") - " + RandomStringUtils.randomNumeric(minLength, maxLength));
    }
}

Example 1

count = 5

In the first example, we use the first variation of the method where we specify the exact length of the generated string. The method generates the random string 21702 of length five consisting of only digits.

Example 2

minimum length = 5
maximum length = 10

In the second example, we use the second variation of the method where we specify the minimum and maximum length of the generated string. The method generates the random string 85015 of length five consisting of only digits.

Output

The output of the code is as follows:

The output of RandomStringUtils.randomNumeric when the length is 5 - 21702
The output of RandomStringUtils.randomNumeric when the (minlength, maxlength) is (5, 10) - 85015