Generate random Integer within given range

In this example we shall show you how to generate a random Integer within a given range, using random() method of Math. The class Math contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions. To generate a random Integer within a given range one should perform the following steps:

  • Use random() method of Math to get a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.
  • Multiply the result to a number. For example, multiply the result to 100. The maximum of this is 100 and the minimum 0.
  • You can also add a number to the result. For example add 50 to the result. Now the range is between 50 and 150,

as described in the code snippet below.  

package com.javacodegeeks.snippets.core;

public class RandomIntWithinGivenRange {

	public static void main(String args[]) {

		// This example will return a random integer 
		// in the range [-50,50]
		int random1 = (int)(Math.random()*100)-50;
		System.out.println("Value 1 = " + random1);
		// This example will return a random integer
		// in the range [50,150]
		int random2 = (int)(Math.random()*100)+50;
		System.out.println("Value 2 = " + random2);


Value 1 = -43
Value 2 = 111

This was an example of how to generate a random Integer within a given range in Java.

Byron Kiourtzoglou

Byron is a master software engineer working in the IT and Telecom domains. He is an applications developer in a wide variety of applications/services. He is currently acting as the team leader and technical architect for a proprietary service creation and integration platform for both the IT and Telecom industries in addition to a in-house big data real-time analytics solution. He is always fascinated by SOA, middleware services and mobile development. Byron is co-founder and Executive Editor at Java Code Geeks.
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