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How to generate random long values in Java

abhilash

We can generate random long values with the nextLong method of the RandomUtils class.

nextLong is a static method that can generate random long values.

There are two variations of the method:

  • One takes the range as parameters and generates random long values within the specified range.
  • The other generates random long values within zero to Long.MAX_VALUE.

How to import RandomUtils

RandomUtils is defined 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>

Refer to the Maven Repository for other versions of the commons-lang package.

You can import the RandomUtils class as follows.

import org.apache.commons.lang3.RandomUtils;

Method 1

Syntax

public static long nextLong(final long startInclusive, final long endExclusive)

Parameters

  • startInclusive: The lower bound of the range or the smallest value that can be returned.
  • endExclusive: The upper bound of the range that is not included.

Return value

nextLong returns a random long value within the given range.

Method 2

Syntax

public static long nextLong()

Parameters

The method takes no parameters.

Return value

The method returns a random long value within zero to Long.MAX_VALUE.

Code

import org.apache.commons.lang3.RandomUtils;

public class Main {

    public static void main(String[] args) {
        long lowerBound = 1000;
        long upperBound = 234543;
        System.out.printf("Random long generated between [%s, %s) is %s", lowerBound, upperBound, RandomUtils.nextLong(lowerBound, upperBound));
        System.out.printf("\nRandom long generated between [0, Integer.MAX_VALUE) is %s", RandomUtils.nextLong());
    }
}

Example 1

  • Lower bound: 1000
  • Upper bound: 234543

The parameterized method is used here to generate a random long value. The method accepts the lower and upper bounds as parameters.

Example 2

  • Lower bound: 0
  • Upper bound: Long.MAX_VALUE

The method that doesn’t accept any parameters is used here to generate a random long value.

Expected output

Random long generated between [1000, 234543) is 2247
Random long generated between [0, Integer.MAX_VALUE) is 4851981442751655696

When you run the code, your output may be different because a random number is generated.

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