How to Generate Random Numbers Within a Specific Range in Java?

Random Number Generation in Java

When crafting programs in Java, a common requirement arises: obtaining random numbers. This article delves into techniques for generating random numbers within a specified range, addressing challenges associated with bounding the outputs of Math.random().

Bounding Math.random() Values

Math.random() generates floating-point values between 0 and 1. To constrain these values within a specific range, manipulation is necessary. Two approaches prevail:

1. Multiplicative Bounding:

This approach multiplies the random value by the difference between the lower and upper bounds of the desired range. For instance, to obtain a random number between 1 and 50:

double random = Math.random() * 49 + 1;

2. Casting Bounding:

Here, casting is performed to convert the floating-point random value to an integer and apply the lower and upper bounds:

int random = (int)(Math.random() * 50 + 1);

Alternative Solution: Random Class

The java.util.Random class provides a more comprehensive solution for generating random numbers. Here's an example:

import java.util.Random;

Random rand = new Random();

// Obtain a number between [0 - 49].
int n = rand.nextInt(50);

// Add 1 to the result to get a number from the required range
// (i.e., [1 - 50]).
n += 1;

Select the approach that best suits your specific use case and enjoy the flexibility of generating random numbers in Java.

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