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How To Generate Random Number In Java

Last Updated : Mar 11, 2024

How To Generate Random Number In Java

In this article we will show you the solution of how to generate random number in java, creating random integers is a necessary part of writing Java apps. Many programmes have the ability to generate numbers at random, for example, many applications employ the OTP to validate the user.

Dice is the best illustration of random numbers. We receive a random number ranging from one and 6 when we throw it.

This part will teach us what a random number is and how to create them in Java.

Random numbers are those that draw from a huge pool of possible values and choose one using a mathematical method. It meets the following two criteria:

  • The generated values were evenly spaced out throughout a specific range.
  • Based on previous and present values, one cannot predict the value of something in the future.

Java provides three methods and classes for generating random integers.

  • Making use of the random() Method
  • Implementing the Random Class
  • Making use of the ThreadLocalRandom Class
  • Making use of the ints() Method.

Utilizing a Java Random class from the java.util package is another method for producing random numbers.

It creates a constant stream of seemingly random numbers. Any data type, including float, double, boolean, long, and integer, can have a random number generated for it.

Follow the instructions below if you plan to utilize this class to create random numbers:

  • First, import the class java.lang.Random.
  • The Random class can be created by creating an object.
  • You can use any of the following methods:
  • nextInt(int bound)
  • nextInt()
  • nextFloat()
  • nextDouble()
  • nextLong()
  • nextBoolean()

Each of the aforementioned approaches yields the following pseudorandom, evenly distributed value from the output of this random number generator.

Random values between 0.0 / 1.0 are generated by the nextDouble() or nextFloat() methods.

The parameter bound (upper), which must be positive, is accepted by the nextInt(int bound) method. It produces a random number that falls between 0 and bound-1.

Any data type, including float, double, boolean, long, and integer, can have a random number generated for it. To generate random numbers with this class, follow these guidelines:

  • First, import the class by using java.util.concurrent.ThreadLocalRandom.
  • Call the matching method that you want to use to create random numbers.
  • nextInt()
  • nextDouble()
  • nextLong()
  • nextFloat()
  • nextBoolean()

All of the aforementioned methods replace their respective counterparts in the Random class & return the appropriate value.

  • nextInt(int bound)
  • nextDouble(int bound)
  • nextLong(int bound)

The aforementioned techniques parse an upper parameter constraint that needs to be positive.

In between 0 (inclusive) as well as the specified bound, it returns an equivalent randomly generated value. If the bound is negative, IllegalArgumentExcetion is thrown.

  • nextInt(int origin, int bound)
  • nextDouble(int origin, int bound)
  • nextLong(int origin, int bound)

The techniques mentioned above parse the parameters bound and origin.

The bound provides the upper bound whereas the origin specifies that lowest value that will be returned.

It gives back a value created randomly between the bound and the origin (inclusive) given (exclusive).

Additionally, if indeed the origin is greater or equal to the bound, IllegalArgumentExcetion is thrown.

The Random class now has a new method called ints() that was added in Java 8. Before utilising the method, you should import the java.util.Random package.


The nextInt() method call produces identical pseudorandom int numbers. An endless stream if pseudorandom int integers are returned.

long streamSize: ints

The method parses the long-type streamSize parameter. The quantity more values to also be generated is specified.

The nextInt() method call produces identical pseudorandom int numbers.

A stream of int values that were produced at random is also returned. If indeed the stream size is below zero, it raises the IllegalArgumentException exception.

Step By Step Guide On How To Generate Random Number In Java :-

import java.lang.Math;
public class TalkersCode
public static void main(String args[])
System.out.println("first Random Number: " + Math.random());
System.out.println("second Random Number: " + Math.random());
System.out.println("third Random Number: " + Math.random());
System.out.println("fourth Random Number: " + Math.random());
  1. The import function is first defined as java.lang. Math
  2. Next, a class named talkerscode is created.
  3. Next, we define argos as a public static void main string.
  4. Then, we use math.random to generate random integers.

Conclusion :-

Numerous methods for various mathematical operations are available in the Java Math class.

One of these is the random() method. It is a static method from the Math class.

It only produces random numbers of the double type that are equal or superior to 0.0 as well as less than 1.0.

We need to import this java.lang.Math before we may make use of the random() technique.

I hope this article on how to generate random number in java helps you and the steps and method mentioned above are easy to follow and implement.

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